Media playback is unsupported on your device Media caption Russian President Vladimir Putin: "It is an unconstitutional coup and a military seizure of power" 
 
 Russian President Vladimir Putin has said there is no need yet to send troops into Ukraine, but that Moscow is ready to protect its citizens. 
 
 His comments come as armed men, who Mr Putin says are not Russian troops but pro-Russian self-defence groups, surround army bases in Crimea. 
 
 Kiev and the West have accused Russia of invading the Ukrainian peninsula. 
 
 US Secretary of State John Kerry is in Kiev, amid intensive diplomatic efforts to resolve the escalating crisis. 
 
 Speaking after talks with interim President Olexander Turchynov, Prime Minister Arseniy Yatsenyuk and other new government figures, Mr Kerry said Ukraine had entered a "new phase" of its struggle for freedom. 
 
 It is what the international community fears most: a confrontation that spills out of control and leads to war Resistance proves problem for Russia 
 
 He reaffirmed the US commitment to Ukraine's "sovereignty and territorial integrity", and condemned Russian aggression, saying there was no need for Moscow to pursue military action rather than diplomacy if it was concerned about its citizens. 
 
 If Russia chose to ignore appeals to pull back its forces, the US and its partners would have "no choice" but to seek to further "isolate Russia, politically, diplomatically and economically", he said. 
 
 Mr Kerry is bringing an offer of a $1bn (£600m; 720m euros) package to help ease its looming financial crisis. 
 
 Media playback is unsupported on your device Media caption The military strengths of Russia and Ukraine compared - in 60 seconds 
 
 Image copyright Reuters Image caption Mr Kerry is offering Ukraine a $1bn package to help it through an energy crisis 
 
 Image copyright AFP Image caption On arrival in Kiev, Mr Kerry first paid tribute to those killed in the Maidan protests 
 
 In other diplomatic developments 
 
 Russian Foreign Minister Sergei Lavrov is meeting EU foreign policy chief Catherine Ashton in the Spanish capital, Madrid 
 
 The EU is considering paying the $2bn which Ukraine owes to Russia in gas bills, AFP news agency quotes EU Energy Commissioner Guenther Oettinger as saying 
 
 Moscow has agreed to attend an extraordinary meeting of Nato members on Wednesday 
 
 According to Reuters news agency, Mr Yatsenyuk said that high-level talks were taking place between Russian and Ukrainian ministers. There was no immediate confirmation from Moscow, which says the new government in Kiev is illegitimate. 
 
 Ships 'blockaded' 
 
 Crimea has become the major focus of post-uprising Ukraine, as troops in what appear to be Russian uniforms surround Ukrainian military bases and other installations. Russia is de facto in control of the peninsula. 
 
 Tensions were especially high at Belbek airbase near Sevastopol, the port city which is the base of Russia's Black Sea Fleet. Early on Tuesday, pro-Russian forces fired warning shots in the air, and Ukrainian troops later marched away from the base. 
 
 Meanwhile, two Ukrainian warships are reported to be blocked by a Russian ship in the port of Sevastopol. 
 
 Ukraine says some 16,000 Russian troops have arrived in Crimea in recent days. 
 
 But at a news conference in Moscow, Mr Putin insisted that the heavily armed men who had taken over official buildings in Crimea and blocked Ukrainian troops in their barracks were pro-Russian "local forces of self-defence" - not Russian troops. 
 
 The BBC's Mark Lowen in the Crimean town of Bakhchysarai - north of Sevastopol - said one such armed man had told him on Monday he was "a Russian soldier, based usually in Sevastopol". 
 
 When asked whether he thought it was right for Russia to blockade Ukrainian bases he replied: "If you ask me as a person, then no it's not right. But I'm following orders." 
 
 Image copyright Getty Images Image caption A Ukrainian officer (centre) negotiates with troops under Russian command at Belbek air base 
 
 Image copyright AP Image caption Ukrainian troops remain blockaded in Perevalne military base in Crimea 
 
 Image copyright Reuters Image caption Pro-Russian protests have been held in cities in eastern Ukraine, including here in Donetsk 
 
 At the scene The rumoured deadline had many on edge. It has been peaceful overnight, though there were reports of a couple of warning shots fired at Sevastopol airport. There is an atmosphere of fear and conjecture. Russian soldiers and local self-defence units are still at key installations, including Ukrainian military bases. At one base, in Bakhchisaray, a 22-year-old Russian soldier, Vitaly, said they were guarding the base against Ukrainian nationalists. "The people want us here, this is not an occupation," he said. A Ukrainian soldier there said "it's a Russian provocation. I answer to my government in Kiev - I'm not going anywhere". At the front gate was a pro-Russian civilian group with blaring music. One of them said they were protecting locals from "fascism". Does Russia have a case? Military balance of power 
 
 Mr Putin said the toppling of President Viktor Yanukovych last month following mass protests was an "anti-constitutional coup and armed seizure of power". 
 
 He also insisted that Mr Yanukovych - whom Ukraine's parliament voted to impeach on 22 February - was still the legitimate president, though admitted: "I don't think he has a political future." 
 
 Ukraine was in "chaos", he said, with "nationalists" and "anti-Semites" roaming the streets of Kiev and other cities. 
 
 If Russian-speaking people in eastern Ukraine asked for Russia's help, or if there were signs of anarchy, "we reserve the right to use all means," he said. 
 
 He accused the West of encouraging the street protests. 
 
 Mr Yanukovych is now in Russia - Mr Putin said Russia had had to help him, "otherwise he'd just have been killed". 
 
 Hundreds of pro-Russian demonstrators have been rallying in Donetsk and other parts of eastern Ukraine, rejecting the new pro-Western leadership in Kiev. 
 
 There is international concern about the economic fallout from the crisis. On Monday the rouble plunged to new lows against the dollar and euro, but global markets steadied on Tuesday. 
 
 Ukraine's ailing economy relies on Russian gas - and on Tuesday the head of Russia's gas monopoly Gazprom, Alexei Miller, said that from April Ukraine would no longer get discounted gas, because it had violated its agreements. ||||| Media playback is unsupported on your device Media caption The BBC's Ben Brown says Russian forces prevented him from speaking to Ukrainian staff at the gates 
 
 Russian Foreign Minister Sergei Lavrov has held talks with counterparts from the US and key EU states to try to resolve the crisis in Ukraine. 
 
 After the talks Mr Lavrov said it was agreed to continue discussions in the coming days but admitted that everyone was "concerned" at events. 
 
 US Secretary of State John Kerry said the talks were "tough" but that there were some concrete ideas to work on. 
 
 The EU earlier offered 11bn euros ($15bn; £9bn) of aid to Ukraine. 
 
 European Commission President Jose Manuel Barroso said the package of loans and grants over the next couple of years was "designed to assist a committed, inclusive and reforms-oriented government" in Kiev. 
 
 Analysis In return for its billions, the EU wants an inclusive government in Ukraine. That does not sound all that far off from what the Russian foreign minister said when he demanded a return to the 21 February agreement signed in Kiev. It spoke of a government of national unity. However, I am told that is the wrong interpretation, as the EU believes the administration it is seeking is already in place. As for the money, some 600m euros is already there. The rest of the 11bn euros needs to be signed off by member states and the European Parliament. Of that, some 5bn euros will come directly from the biggest investor in Ukraine, the European Bank for Reconstruction and Development (EBRD). While Mr Barroso said the money would be handed over in the next two years, the EBRD is talking about the next five or six. So while this is a substantial sum, it will be disbursed slowly. 
 
 Ukraine's finance ministry has predicted it needs $35bn to rescue the economy. 
 
 The EU also froze the assets of 18 Ukrainians, accused of involvement in a deadly crackdown on protesters. 
 
 In other developments: 
 
 Hundreds of pro-Russian demonstrators have stormed the regional government building in Donetsk for the second time in recent days 
 
 Gunmen in Crimea threatened the UN secretary-general's envoy, Robert Serry, but he is reported safe 
 
 Russian forces have seized two Ukrainian missile-defence sites in Crimea, according to unconfirmed reports 
 
 Russian President Vladimir Putin and German Chancellor Angela Merkel discuss crisis in telephone call 
 
 Nato pledge 
 
 Mr Lavrov met Mr Kerry and counterparts from the UK, Germany and France on the sidelines of a long-planned conference on Lebanon in Paris. 
 
 The Russian minister said it was agreed that all sides needed to respect an EU-brokered peace deal signed last month. 
 
 The US state department, however, denied any agreement had been reached. 
 
 The 21 February deal granted major concessions to the opposition, but pro-Russian President Viktor Yanukovych fled before it could be implemented. 
 
 One thing that makes Vladimir Putin mad is the feeling that he is being deceived Putin's calculations in Ukraine Media see new phase in Kremlin approach 
 
 "We had a long day of discussions on Ukraine," Mr Lavrov said. 
 
 "We are all concerned at what is happening there. We agreed to continue those discussions in the days to come... and that's it." 
 
 Mr Kerry said he had some concrete ideas to take back to President Barack Obama, adding: "I'd rather be where we are today than where we were yesterday." 
 
 Nato and Russia held parallel talks in Brussels. 
 
 Afterwards, Nato Secretary-General Anders Fogh Rasmussen said the organisation was reviewing all cooperation with Russia and was stepping up its engagement with the government in Kiev. 
 
 The US and Russia had appeared far from compromise in the lead-up to the Paris talks. 
 
 The US wants independent observers in the flashpoint region of Crimea and direct talks between Kiev and Moscow. 
 
 Image copyright Reuters Image caption Troops believed to be Russian servicemen are in control of Ukrainian military bases in Crimea 
 
 Image copyright AP Image caption Mourners at Kiev's Independence Square remember the 88 protesters who died in clashes with police 
 
 Image copyright AP Image caption Pro-Russian protesters stormed the Donetsk government building hours after they were forced out 
 
 Russia was expected to call for greater representation for Ukraine's Russian-speaking areas in the Kiev government. 
 
 Leaked call 
 
 In the US, Pentagon chief Chuck Hagel announced plans to expand US military co-operation with Poland and Baltic states. 
 
 Analysis The first of two sophisticated naval landing ships being built in France for the Russian navy is to set sail on Wednesday afternoon for its initial sea trials. The vessel - the Vladivostok - is based upon the Mistral class already in service with the French navy. The deal was signed in June 2011. The vessel can operate smaller landing craft and helicopters and would significantly enhance Russia's amphibious capabilities. The deal to sell such a sophisticated piece of equipment to Moscow has always been controversial; even more so today given the crisis in Ukraine with the French government insisting that if there is no de-escalation of tensions, then rapid EU sanctions could follow. The timing is perhaps a little delicate for Paris, with high-level talks on the crisis under way in the French capital. But at least this is not the Vladivostok's sister vessel that is putting to sea - that is to be named Sevastopol. 
 
 He said the US would step up joint aviation training with Poland, and increase its participation in Nato's mission to police the air space of Baltic countries. 
 
 The announcement was a direct response to concerns raised last week by Poland, he said. 
 
 Meanwhile, a recording of a phone conversation between EU foreign policy chief Catherine Ashton and Estonian Foreign Minister Urmas Paet has been leaked on the internet. 
 
 In the recording, Mr Paet told Baroness Ashton that there was an "increasing understanding" in Ukraine that ousted President Viktor Yanukovych's government was not responsible for the deaths of police and protesters during clashes last month in Kiev. 
 
 He said some Ukrainians believed elements from within the new regime in Kiev had employed snipers. 
 
 He said Ukrainian doctor Olga Bogomolets had told him that victims from both sides were shot by snipers using the same weapons. 
 
 However, Dr Bogomolets told the UK's Telegraph newspaper that she had never had access to victims from the government side and was unable to comment on how they had been killed. 
 
 Mr Paet confirmed that the conversation with Baroness Ashton had taken place on 26 February. 
 
 Media playback is unsupported on your device Media caption Sergei Lavrov accused protesters of conducting an "armed coup d'etat" 
 
 In a news conference on Wednesday, he called for an inquiry into the deaths in Kiev, but warned against using his comments to discredit the new government. 
 
 "I call for journalists to treat this recording very carefully. I was talking about the theories there were about what happened in Ukraine," he said. 
 
 Mr Yanukovych fled Ukraine shortly after the bloodshed and is now in Russia. 
 
 Moscow has since flooded the Crimea region with military personnel, claiming that Mr Yanukovych had asked for their help. 
 
 The Organisation for Security and Co-operation in Europe (OSCE) says it has sent 35 unarmed military monitors to Ukraine in response to a request from Kiev. ||||| The Ukrainian army braces for the worst while diplomatic efforts on Crimea in London fall short. (Reuters) 
 
 The Ukrainian army braces for the worst while diplomatic efforts on Crimea in London fall short. (Reuters) 
 
 Deadly clashes broke out in eastern Ukraine, officials said Saturday, after an 11th-hour U.S. effort to resolve the growing confrontation with Russia failed and Moscow shipped more troops and armor into the flash-point Crimea region. 
 
 The shootout between pro-Russian and pro-Ukrainian demonstrators took place overnight Friday in the eastern city of Kharkiv and left two people dead, acting interior minister Arsen Avakov wrote on his Facebook page Saturday. Tatiana Gruzinskaya, spokeswoman for the mayor, said the incident happened after a group of Russian separatists approached the offices being used by pro-Ukrainian activists. It was not yet clear whether the fatalities were pro-Russian or pro-Ukrainian, and activists on both sides were arrested, officials said. 
 
 The clash is likely to add to fears that Russia will expand its intervention beyond Crimea and into eastern Ukraine. While Russia has blamed such clashes on right-wing Ukrainians and on the new government, Avakov accused Russia of inciting the violence. “Hired provocateurs from a neighboring country are staging professional provocations,” Avakov said. 
 
 With a vote planned Sunday in Crimea on breaking away from Ukraine and rejoining Russia, Secretary of State John F. Kerry warned against a “backdoor annexation” by Russia of the strategic Black Sea peninsula. But Kerry conceded that six hours of talks in London with Russia’s top diplomat neither stopped Sunday’s vote nor opened a new diplomatic path for Moscow to step back from the Cold War-tinged standoff. 
 
 The most significant U.S. and European sanctions against Russia since the collapse of the Soviet Union appeared all but certain. 
 
 1 of 29 Full Screen Autoplay Close Skip Ad × Kerry in Europe to discuss Ukraine View Photos U.S. Secretary of State John F. Kerry on Friday morning held talks with Russian Foreign Minister Sergei Lavrov in a diplomatic push to ease the crisis over Russia’s military presence in a southern region of Ukraine. Caption U.S. Secretary of State John F. Kerry on Friday morning held talks with Russian Foreign Minister Sergei Lavrov in a diplomatic push to ease the crisis over Russia’s military presence in a southern region of Ukraine. March 14, 2014 U.S. Secretary of State John F. Kerry waits with staff members for a meeting with Russian Foreign Minister Sergei Lavrov at Winfield House, the home of the U.S. ambassador in London. Ahead of the meeting, Kerry said he hoped to end a standoff that threatens to divide Ukraine and lead the United States and Europe to impose economic and other sanctions against Moscow. Brendan Smialowski/Reuters Buy Photo Wait 1 second to continue. 
 
 “We don’t have a common vision of the situation,” Russian Foreign Minister Sergei Lavrov said after the crisis talks. 
 
 No agreements were reached, Lavrov told reporters. He stressed that Russia insists on Crimea’s right to hold the referendum. He said Russia would decide after the vote on how to respond. 
 
 When pressed about whether Russia would annex Crimea after the vote, he said, “There are no what-ifs in politics.” 
 
 Voters in Crimea will decide whether to secede from Ukraine and join Russia or remain part of Ukraine with greater autonomy. 
 
 The vote will be held under the eyes of Russian troops who effectively took control of Crimea late last month after protesters overthrew the Ukrainian government. The Crimean regional parliament has already voted to leave Ukraine, and the traditionally pro-Russian population of Crimea is expected to approve the idea as well. 
 
 [READ: Lavrov is the Russian foreign minister the U.S. loves to hate] 
 
 Moscow’s tightening grip on Crimea and the gathering of Russian troops along the two countries’ border have unnerved Ukrainians and left the country’s fledgling government concerned about further Russian military action. Kerry said the United States was “deeply concerned” about those deployments. 
 
 The United States and other nations have been dangling a diplomatic solution for Russia, tacitly acknowledging that the referendum would produce a pro-Russia outcome while suggesting that Russia could avert further escalation by leaving Crimea’s precise status vague. 
 
 But Kerry said Lavrov had made it clear that Russian President Vladimir Putin was not prepared to take that step. Lavrov said Russia will “respect” the results of the plebiscite, and it was clear from Kerry’s tone that the United States fears full annexation. 
 
 “We did not find common ground today on the way ahead,” said a senior U.S. official who spoke on the condition of anonymity to describe the roughly six hours of intensive discussions Friday. 
 
 In Washington, President Obama stressed the continued need for “a strong message to Russia that it should not violate the integrity and sovereignty of its neighbor.” 
 
 The European Union is expected to impose travel bans and asset freezes Monday on Russians accused of complicity in Moscow’s military incursion and the intimidation of Crimea. The E.U. on Friday identified more than 120 individuals as potential sanctions targets. 
 
 The White House announced Friday that Vice President Biden will travel to Poland and Lithuania next week to discuss Ukraine and other issues with regional leaders. 
 
 [Russia supporters in eastern Ukraine pose challenges to government] 
 
 In London, Lavrov insisted that Russia had no plans to invade Russian-speaking eastern Ukraine. But he echoed a statement issued in Moscow by the Foreign Ministry warning that Russia “reserves the right to take people under our protection.’’ Thursday night clashes between pro- and anti-Russian demonstrators in the Ukrainian city of Donetsk led to the death of one protester. 
 
 That protester was identified as Dmytro Chernyavskiy, the press secretary of the regional branch of a pro-Ukrainian ultranationalist party. Donetsk regional governor Sergei Taruta said in Kiev on Friday that the fighting was provoked by “non-Ukrainian citizens” and pro-Russian activists. 
 
 On Saturday in Kiev, Ukraine’s Foreign Minister Andriy Deshchytsa called on Russia to “stop interferring” in eastern Ukraine, adding that authorities here could handle issues of law and order in the region “ourselves.” He described threatening statements from Russia’s Foreign Ministry as an attempt to “provoke” an escalation of the tense situation in the east. 
 
 Deshchytsa called for U.N. monitors to fan out across southern and eastern Ukraine to independently assess the situation on the ground. 
 
 He also reiterated Kiev’s position that Sunday’s referendum in Crimea would be “illegal” and would not be recognised by the international community. He emphasized the new government’s desire to avoid any military conflict, and referred to the current stand off as more of a “diplomatic war.” But he added he would travel to Brussels on Monday to meet with NATO’s secretary general to discuss “military and technical cooperation.” 
 
 He said the U.N. security council was scheduled to discuss a motion on Ukraine later Saturday, but acknowledged a likely Russian veto. 
 
 Russia’s Interfax news agency reported Friday that a newly announced series of military exercises near Ukraine’s eastern border had expanded to include training missions for fighter jets and helicopters. Ukrainian military officials reported the seizure of another base in Crimea, a radar facility taken by Russian soldiers at about 3 a.m. Friday. 
 
 A Ukrainian defense ministry official said a column of about 50 armored vehicles from the Russian Federation were observed late Friday night moving from the city of Feodosia to Dzhankoi in northern Crimea. Vladislav Seleznyov said more Russian troops have moved in to occupy Ukrainian military bases that had been abandoned long before the crisis began. 
 
 In the Crimean capital of Simferopol, campaigning for Sunday’s referendum was in high gear Friday. Vans with megaphones blared Russian music in the streets around the regional parliament, where a large Russian flag already flies. 
 
 Vasilyev Maxim, an official from the Russian city of Kursk, said he drove to Crimea with thousands of Russian flags purchased with $10,000 of his own money to distribute ahead of the vote. “In 30 years, the history books will say Putin took back Crimea to rebuild our country,” he said. “And no one will remember Kerry or that Obama had anything to do with the situation.” 
 
 A new poll suggests the Crimean vote to join Russia will be overwhelming. 
 
 In a GFK poll of 600 residents taken Thursday and Friday, 70 percent said they will vote to become part of Russia, and just 11 percent said they will vote to restore Crimea’s status as part of Ukraine. If survey-takers were offered more options, they told posters, 19 percent would vote for independence. But a majority, 54 percent, would still favor becoming joining Russia. 
 
 It remains unclear how Moscow will consider Crimea’s status, said Sergei Markedonov, an associate professor of regional studies and foreign policy at the Russian State University for the Humanities. 
 
 Putin said at a recent news conference that Russia did not intend to annex Crimea, Markedonov pointed out, and the president has not made any public statements to the contrary since then. Crimea could emerge as a de facto state like Nagorno-Karabakh in the southern Caucasus, he said. 
 
 Lavrov said at his news conference that there were other precedents for Crimean secession besides the often-cited example of Kosovo. He referred to the Comoros Islands, which declared independence from France. 
 
 The talks at the sumptuous central London home of the U.S. ambassador were always a long shot to succeed. 
 
 Lavrov, a quick-witted diplomat who is often jocular when meeting with Kerry, was grim-faced as he entered the meeting. Although he speaks flawless English, he stuck to Russian at his news conference and spoke through an interpreter as he referred to the “difficult situation we are in.” 
 
 The mood may have lightened somewhat as the session continued into the afternoon, far longer than planned. Lavrov’s spokeswoman tweeted a picture of the two men kicking a soccer ball in their dress shoes as they strolled the park-like grounds of the ambassador’s residence. 
 
 Lally reported from Moscow. Karla Adam in London and Carol Morello and Pamela Constable in Simferopol contributed to this report. ||||| A U.N. envoy was in a standoff with armed men who blocked his car. 
 
 From left, Russian Foreign Minister Sergey Lavrov, French President Francois Hollande, Italian Foreign Minister Federica Mogherini and U.S. Secretary of State John Kerry talk during a break at the Elysee Palace in Paris on March 5. (Photo: Alain Jocard, AP) Story Highlights Top diplomats converge on Paris 
 
 Putin has signaled he is not ready for war 
 
 NATO meeting with Russia in Brussels 
 
 KIEV, Ukraine — Negotiations to end the crisis in Crimea foundered Wednesday over Russia's refusal to recognize Ukraine's new leaders much less sit down with its ambassador. 
 
 "I wish I could give you some good news," said Polish Foreign Minister Radoslaw Sikorski outside the talks in Paris. "But unfortunately it hasn't been possible to bring together the foreign ministers of Ukraine and Russia." 
 
 Wednesday's gathering of diplomats in Paris came a day after Russian President Vladimir Putin appeared to calm fears of further military incursion by saying he has no intention to "fight the Ukrainian people." Russian troops took over key points of Crimea after the parliament in Kiev ousted Ukraine's pro-Moscow president, Viktor Yanukovych. 
 
 U.S. Secretary of State John Kerry, Russian Foreign Minister Sergey Lavrov and several European diplomats met Wednesday to discuss whether there are peaceful ways to end Russia's occupation of Crimea, a peninsula where many Russian-speaking people say they want more autonomy from Kiev. 
 
 But Lavrov refused to meet with the Ukraine ambassador, saying he represents an "illegitimate" government. 
 
 "I don't think any of us had an anticipation that we were coming here at this moment, in this atmosphere of heightened tension and confrontation, that we were suddenly going to resolve that here, this afternoon," Kerry said after talks ended for the day. 
 
 To induce Crimea to lean toward Europe rather than Russia, the European Union on Wednesday matched a $15 billion aid offer that Putin had made to help with Ukraine's financial woes. 
 
 The United States offered an additional $1 billion in loan guarantees to help Ukraine reduce its energy reliance on Russia, which supplies the majority of Ukraine's natural gas. 
 
 WATCH: Pro-Russian crowds chant as envoy departs 
 
 In Ukraine, Prime Minister Arseniy Yatsenyuk blamed Putin for causing one of the sharpest international crises in Europe since the end of the Cold War. Despite a denial from Lavrov, Russian troops have fanned into Crimea and are controlling border crossings and bases, as well as encouraging Ukrainians to rise up against the government, he said. 
 
 "Mr. President (Putin), stop this mess," Yatsenyuk said. "Let me remind Mr. Putin that this government was supported by the constitutional majority of Ukrainian members of parliament. We are legitimate." 
 
 Ukrainians who helped oust Yanukovych say Putin had planned all along to invade and was just waiting for an excuse. 
 
 "It is all about the Russians' ambitions," said Roman Yaruchik, 40, of Kiev. "It's obvious that Russian troops entered Crimea even before their parliament ratified sending the troops to invade Crimea." 
 
 Putin claims that Yanukovych, whom he has given sanctuary in Russia, remains the true president. The Ukraine government has issued a warrant for his arrest on charges of murder for the shooting of more than 80 protesters in Kiev. 
 
 U.N. special envoy to Ukraine Robert Serry took refuge March 4 in a coffee shop from an armed group in Crimea who also blocked him from leaving. He later agreed to end his mission and leave the country. (Photo: ATR TV) 
 
 In Crimea, Russian troops held onto positions outside Crimean cities and pro-Russian militia members blocked Ukraine military bases to prevent soldiers from getting out. 
 
 A special U.N. envoy cut short his mission in Crimea on Wednesday after being threatened by 10 to 15 armed men and ordered to leave the region, U.N. officials said. 
 
 ITV News' Europe Editor James Mates reported that envoy Robert Serry left his car, which had been blocked by the armed men shouting, "Putin! Putin!," and took refuge in a nearby coffee shop. 
 
 AID PACKAGE: U.S. pledges $1 billion aid to Ukraine 
 
 The United States and European Union have threatened Russia with economic sanctions if it does not back down. A Russian politician told the RIA Novosti news agency that the Russian Senate was preparing a bill that would allow for the confiscation of American and European corporate assets located in Russia were sanctions to be introduced. 
 
 CRISIS IN CRIMEA: Russia's Putin appears to blink in Ukraine 
 
 Read or Share this story: http://usat.ly/1c7R7O4 ||||| Media playback is unsupported on your device Media caption Ukrainian soldiers are trapped on their own base as Daniel Sandford reports 
 
 Ukraine has ordered a full military mobilisation in response to Russia's build-up of its forces in Crimea. 
 
 Prime Minister Arseniy Yatsenyuk said Ukraine was "on the brink of disaster". 
 
 In Crimea, Ukrainian soldiers faced off with Russian soldiers surrounding their bases while the Russian army is said to be digging trenches on the border with mainland Ukraine. 
 
 Media playback is unsupported on your device Media caption US Secretary of State John Kerry said Russian troops moving into the Ukraine region of Crimea was a "brazen act of aggression" 
 
 US Secretary of State John Kerry has warned Russia could be ejected from the Group of Eight developed nations. 
 
 Russian President Vladimir Putin, he said, was "not going to have a Sochi G8, he may not even remain in the G8 if this continues," referring to a planned summit in Russia in June. 
 
 "He may find himself with asset freezes, on Russian business. American business may pull back, there may be a further tumble of the rouble. 
 
 "You just don't in the 21st Century behave in 19th Century fashion by invading another country on completely trumped-up pretext," Mr Kerry told the CBS program Face the Nation. 
 
 The facts on the ground are such that Russia, to a large extent, is already in control there Moscow's Ukraine gamble 
 
 The UK has joined the US, France and Canada in suspending preparations for the Sochi summit. 
 
 Nato is conducting emergency talks, saying Russia's actions threaten "peace and security in Europe". 
 
 US President Barack Obama called Russian troop deployments a "violation of Ukrainian sovereignty". 
 
 Russian soldiers continue to occupy key sites on the Crimean peninsula, including airports and communications hubs, although there has been no actual violence and they have been openly welcomed by some sections of the population. 
 
 In the east Ukrainian city of Donetsk, apparent members of the disbanded elite police riot unit Berkut appeared in full uniform at a pro-Russian rally. 
 
 At the scene Crowds of excited pro-Russian Crimeans have gathered near the gates of the marines' base in Feodosia. A deadline demanding the marines pledge loyalty to the new government in Crimea has passed. Despite threats to attack the base, local Cossacks, who act as law and order here, continue to stand in a chain near the gates. Behind the gates I could see freshly-made dugouts, but no-one is inside them at the moment. A couple of marines in sand-coloured flak jackets are manning the gates from the inside. The street leading to the base is blocked by two armoured personnel carriers, with another closer to the gates. When asked whose APCs and soldiers they were, a Cossack said "Russians", but he didn't know whether they came from Black Sea Fleet base in Sevastopol or Russia. From time to time the loudspeaker on a van near to the entrance of the base calls on the marines to recognise the new pro-Russian government in Crimea, and not to act upon "criminal orders from Kiev". Any filming activity in the crowds is risky - we saw cameramen and photographers being harassed. One cameraman had to leave the approach to the base and another was led away by a policeman. Text of Putin's request to use troops What is so dangerous about Crimea? Crimea profile 
 
 In Moscow, police detained dozens of people at anti-war rallies outside the Russian defence ministry and other places in the city centre, while elsewhere in the city a pro-Putin march was held. 
 
 Military build-up 
 
 Ukrainian national security officials announced several other measures on Sunday 
 
 The armed forces would to be put on "full combat readiness" 
 
 Reserves to be mobilised and trained 
 
 Foreign minister to seek help from US and UK leaders in guaranteeing its security 
 
 Emergency headquarters to be set up 
 
 Security to be boosted at key sites, including nuclear plants 
 
 Airspace to be closed to all non-civilian aircraft 
 
 Meanwhile, Ukraine withdrew coast guard vessels from two ports in Crimea and moved them to other bases in the Black Sea and Sea of Azov. 
 
 A Ukrainian army base was surrounded by Russian troops at Perevalnoye, south of the Crimean regional capital Simferopol. An Orthodox priest has arrived in an attempt to mediate. 
 
 In Sevastopol, Ukrainian naval officers found their headquarters occupied by Russian troops and were unable to go to work. 
 
 Admiral Yuriy Ilyn, who was until recently commander of the Ukrainian navy and served briefly as head of Ukraine's armed forces under ousted President Viktor Yanukovych, told the BBC's Christian Fraser at the scene that the armed forces were "hostages of the situation". 
 
 Media playback is unsupported on your device Media caption Admiral Yuri Ilyn: "I'm very sorry that Ukrainian soldiers and sailors are hostages of this situation" 
 
 In the eastern port city of Feodosia, a group of about 100 Ukrainian marines were also blockaded into their base by armed men demanding they pledge loyalty to the region's new pro-Russian authorities. 
 
 In the north of Crimea, at Armyansk on the Isthmus of Perekop, the BBC saw what appeared to be Russian soldiers digging trenches. The isthmus is strategically vital as it joins Crimea to the rest of Ukraine. 
 
 Russian ground troops have been active in Crimea - home to Russia's Black Sea Fleet - for the past few days. 
 
 On Saturday the newly elected pro-Moscow leader of Crimea, Sergiy Aksyonov, appealed to Mr Putin for help to ensure peace on the peninsula. 
 
 The interim government in Kiev does not recognise Mr Aksyonov and his government. 
 
 Image copyright AP Image caption Ukrainian soldiers were surrounded by Russian troops at Perevalnoye, one of several stand-offs on the peninsula 
 
 Image copyright Getty Images Image caption Russian soldiers surrounded a Ukrainian base at Perevalnoye in Crimea 
 
 Image copyright Getty Images Image caption One pro-Russian family posed for photos with the soldiers 
 
 Image caption Russian soldiers were apparently digging trenches on the strip of land joining Crimea to mainland Ukraine 
 
 Image copyright AFP Image caption Apparent members of Ukraine's disbanded riot unit, Berkut, turned out at a pro-Russian rally in the eastern city of Donetsk 
 
 Image copyright Reuters Image caption A march was held in Moscow in support of President Putin's policy on Crimea and Ukraine 
 
 Image copyright AP Image caption But there were small anti-war protests too. "Ukrainians - I am ashamed to be a Russian!" - placard of one protester arrested in Moscow 
 
 Image copyright AP Image caption Meanwhile pro-EU protesters rallied once again in the capital Kiev 
 
 Image copyright AFP Image caption Anti-Putin protesters in Kiev mocked the Russian leader with a placard showing him as Adolf Hitler 
 
 Russian 'violation' 
 
 Media playback is unsupported on your device Media caption Ukraine's interim Prime Minister Arseniy Yatsenyuk says his country is "on the brink of disaster" 
 
 Late on Saturday, Mr Obama held a 90-minute telephone conversation with Mr Putin and urged him to pull forces back to bases in Crimea. 
 
 Mr Putin said Moscow reserved the right to protect its interests and those of Russian speakers in Ukraine. 
 
 President Putin submitted his request for troops to the Russian parliament on Saturday "in connection with the extraordinary situation in Ukraine and the threat to the lives of Russian citizens", the Kremlin said. 
 
 Mr Obama, the White House said, told Mr Putin that the appropriate way to address any concerns was "peacefully through direct engagement" with the Ukrainian government and international mediating bodies.
– Today will be a day of high-stakes diplomacy in Paris, as John Kerry meets with his Russian counterpart for the first time since Russia's invasion of Crimea—an invasion Russia is denying has even happened. Foreign Minister Sergei Lavrov today repeated Russia's assertion that those aren't Russian troops occupying the region, Reuters reports. "If you mean the self-defense units created by the inhabitants of Crimea, we give them no orders, they take no orders from us," he said. Black Sea Fleet troops are in their usual positions, he said, and while "vigilance measures" had been taken, "we will do everything not to allow any bloodshed." Such denials have met derision in the West. Today will also see Lavrov meet with French President Francois Hollande and foreign ministers from Germany and the UK. NATO and Russia are also holding parallel talks in Brussels. Meanwhile, EU officials today offered the Ukraine a $15 billion aid package, to be delivered over two years, the New York Times reports. The Obama administration is simultaneously preparing unilateral sanctions against Russian businesses and individuals, the Washington Post adds. In other news: Pro-Russian protesters are turning away families seeking to bring food to the Ukrainian bases that haven't surrendered to Russian forces, the BBC reports. Russia may have seized control of two Ukrainian missile defense sites, according to an unconfirmed Interfax report. Hillary Clinton took the anti-Russian rhetoric to a new level in an appearance yesterday. "If this sounds familiar, it's what Hitler did back in the '30s," she said, referring to Vladimir Putin's push to give Russian passports to ethnic Russians in the Ukraine, according to the Long Beach Press Telegram. The Nazis resettled ethnic Germans in Germany in the late '30s.