Two Ukrainian fighter jets were shot down in contested airspace near the Russian border Wednesday as tension between the two countries increased a week after a missile struck a passenger jet, killing all 298 people onboard. 
 
 No one could agree on who fired the missiles that hit the fighter jets. Kiev pointed the finger at Russia, while both the Kremlin and pro-Russia separatists said the separatists were responsible. 
 
 Regardless, the fact that the jets were brought down six days after a suspected separatist-fired missile felled Malaysia Airlines Flight 17 stoked fear of a deteriorating military situation. U.S. intelligence agencies believe Russia has supplied the separatists with dozens of additional rocket launchers and military vehicles in the days since the passenger plane was hit. 
 
 The downing of the airliner, which U.S. officials suspect was a mistake, as well as the global outcry that followed, had raised hope that the fighting in eastern Ukraine might cool off. 
 
 But on Wednesday, battles raged in a number of cities in eastern Ukraine’s Luhansk region after several days of fighting in the center of the separatist stronghold of Donetsk. 
 
 Tension also appeared to be ratcheting up between Russia and Western Europe. A spokesman for German Chancellor Angela Merkel said Merkel “thinks rapid decisions are necessary” because of Russia's lack of cooperation in defusing the conflict in Ukraine. 
 
 Kiev’s Su-25 jets were flying fewer than 10 miles from the Russian border over the southeastern Ukrainian towns of Saur Mogila and Dmytrivka on Wednesday when they were shot down, forcing the pilots to eject. Their whereabouts were not immediately known. 
 
 The incident called to mind the days before the Malaysia Airlines attack, when two military transport planes were brought down by separatist missiles. 
 
 What happened Wednesday, however, remained unclear. 
 
 Igor Korotchenko, a Russian military analyst close to the Defense Ministry, told The Times that “the Russian military had nothing to do with the downing of two Sukhoi jets in eastern Ukraine on Wednesday,” adding that he believed the jets “were shot down by local self-defense forces who used portable antiaircraft missiles.” 
 
 Sergei Kavtaradze, an aide to Oleksandr Boroday, one of the self-proclaimed leaders of the so-called Donetsk People’s Republic, told CNN that separatists hit the planes. Separatist forces used shoulder-fired missiles to bring them down, Kavtaradze said. 
 
 But the Ukrainian government was blaming Russia. 
 
 “They were downed not by terrorists,” Andriy Lysenko, spokesman for the National Security and Defense Council, told reporters in Kiev on Wednesday afternoon, using the government's term for the separatists. “‎According to our preliminary information, it was done from across the border.” 
 
 Lysenko cited the fact that the planes were flying‎ at 17,000 feet as partial evidence that the missiles that brought them down couldn't have come from the separatists. 
 
 Asked whether that contradicted the government's belief that separatists had such capability in bringing down Malaysia Airlines Flight 17, which was flying at nearly twice that altitude, Lysenko said, “This is just based on preliminary data.” He did not elaborate, saying only that “an investigation is being arranged.” 
 
 Kavtaradze and Korotchenko’s accounts raised questions too. Each said the planes were downed by shoulder-fired missile, but if the planes were flying at 17,000 feet, they would have been far beyond the reach of the so-called man-portable systems. 
 
 As of Wednesday afternoon, U.S. intelligence agencies said they had not confirmed the Ukrainian government’s claim that the missiles had come from Russia. 
 
 The agencies have confirmed that Russia had sent dozens of additional rocket launchers and military vehicles to separatists within the last week, according to a U.S. intelligence official who was not authorized to speak publicly. 
 
 To assist the separatist forces, the Russian military has taken “mothballed” models of tanks and other equipment out of storage to match equipment used by the Ukrainian military, said the official. Supplying separatists with equipment that matches the Ukrainian government’s armory gives Russia some “plausible deniability” when confronted about arming the groups, the official said. 
 
 In the days after the airliner was shot down, U.S. intelligence satellites also recorded an increase in the number of military vehicles at a Russian base near Rostov-on-Don, a city about 100 miles east of the Ukrainian border, the official said. 
 
 Army Col. Steve Warren, a Pentagon spokesman, told reporters Wednesday that the Russian military continued to maintain as many as 12,000 troops along the Ukrainian border and was still sending equipment into the country. “We know that they [the Russian military] sent, for example, last week a column of over 100 vehicles which included tanks, artillery, multiple-launch rocket systems,” Warren said. 
 
 Russian President Vladimir Putin has denied supplying the separatists with weapons and accused Ukraine of using the downing of the airliner for political ends. 
 
 One day after European Union foreign ministers agreed to impose sanctions on more Russian officials and entities suspected of contributing to the unrest in eastern Ukraine and Crimea, Germany signaled it could soon be taking a firmer stance toward Russia. 
 
 Europe’s largest economy has been less willing than some of its neighbors to criticize Moscow, in part because of strong trade relations between the two countries. But German government spokesman Georg Streiter’s comments to reporters about Merkel on Wednesday suggested that proposals for tougher sanctions could be put into effect quickly after they are presented to European foreign ministers Thursday. 
 
 Merkel has toughened her stance toward Moscow over the last few weeks despite resistance from some in the German business community. 
 
 Also Wednesday, authorities began transporting the bodies of victims of the Malaysia Airlines downing to their families. A total of 40 bodies were loaded onto two planes bound for Amsterdam in a solemn ceremony in the northeastern Ukrainian city of Kharkiv. 
 
 Ukrainian soldiers lined the runway at the airport as the coffins were carried onto the planes, and government officials from several countries offered short speeches. Hans Docter, a representative from the Dutch government, noted solemnly of the victims, “Today, your journey home begins.” 
 
 As the planes landed at Amsterdam’s Eindhoven Airport, a military trumpet sounded in tribute as Prime Minister Mark Rutte and members of the Dutch royal family gathered. Black hearses pulled up on the tarmac to receive the coffins, and a moment of silence was observed. 
 
 steven.zeitchik@latimes.com 
 
 Times staff writers Brian Bennett in Washington, Sergei L. Loiko in Moscow and Henry Chu in London contributed to this report. ||||| A Malaysia Airlines jet was shot down by a surface-to-air missile Thursday over separatist-controlled eastern Ukraine, apparently killing all 298 people on board and dramatically raising stakes in the conflict with the Kremlin-backed forces. 
 
 U.S. intelligence sources said tracking data from spy satellites and radar confirmed that the Boeing 777 en route from Amsterdam to Kuala Lumpur was hit in midair, but they couldn't immediately determine where the missile was launched. 
 
 Ukrainian officials said that Russia had recently supplied the separatists with the mobile Buk surface-to-air launching system, and that the military had not fired any antiaircraft missiles during the conflict with the separatists, which began in mid-April. A number of Ukrainian military aircraft have been shot down by the separatists. 
 
 Although Russia denied involvement, the downing of a passenger jet flying on a heavily traveled international route could sharply increase pressure on Russian President Vladimir Putin, who is accused by the United States, its allies and the Ukrainian government of backing the separatists. 
 
 Before the loss of the passenger jet Thursday, fighting in eastern Ukraine had claimed at least 500 lives in the four months since Russia seized and annexed Ukraine's Crimean peninsula, inspiring the separatists now occupying much of Ukraine's Donetsk and Luhansk regions. 
 
 On Wednesday, the Obama administration stepped up sanctions against Russia for supporting the separatists, targeting some of the country's largest financial institutions, energy companies and weapons firms. 
 
 The loss of another plane dealt a new blow to Malaysia Airlines. It hasn't solved the mystery of what happened to Flight 370, which disappeared on its way from Kuala Lumpur to Beijing in March. 
 
 Ukrainian Security Service communications intercepts made public after the early evening crash of Flight 17 suggest coordination between the separatists and Russian fighters across the border. 
 
 Malaysia Airlines said it lost contact with Flight 17, carrying 283 passengers and 15 crew members, after the aircraft failed to confirm its entry into Russian airspace on schedule at 5:20 p.m. The last contact was recorded about 4:20 p.m. by air traffic controllers. 
 
 The plane “disappeared from radar at [33,000 feet] and then crashed near the city of Shakhtersk in Ukraine's Donetsk region,” the Interfax-Ukraine news agency reported. 
 
 Witnesses in the militant-held crash area about 25 miles west of the Russian border described a gut-wrenching scene. 
 
 “Distorted bodies of dead people and body parts are lying around everywhere in an open field,” Sergei Kavtaradze, a member of the Security Council of the separatists' self-proclaimed Donetsk People's Republic, said in a phone interview. 
 
 Two things were clear from rescue workers' reports, he said: Everyone on board was killed, and it “was not us who shot down the plane because we don't have this hardware.” 
 
 Ukrainian officials disputed that assertion. Anton Gerashchenko, an advisor to the Interior Ministry, said Russia had recently supplied mobile missile systems to the separatists that are capable of taking down a plane at that altitude. 
 
 He demanded that Putin face an international tribunal in the disaster. 
 
 Neither the Kremlin nor major Russian media responded to the accusations that Moscow was behind the jet's downing. But Putin told his economic advisors meeting early Friday that the disaster was Ukraine's fault because of its offensive against separatists. 
 
 “This tragedy would not have happened if there were peace on this land, if the military actions had not been renewed in southeastern Ukraine. And, certainly, the state over whose territory this occurred bears responsibility for this awful tragedy,” the Kremlin news service quoted him as saying. 
 
 Ukrainian officials earlier Thursday accused Russian forces of being behind the downing the day before of a Ukrainian SU-25 ground-support warplane near Donetsk. 
 
 Shortly after the airliner went down, the former Russian special forces officer commanding the separatists in eastern Ukraine claimed responsibility for shooting down an AN-26 Ukrainian military transport plane. 
 
 “We warned them not to fly in our skies,” Igor Strelkov said on his Facebook page. “Peaceful people didn't suffer.” 
 
 He posted a video that later was removed from the page. 
 
 Pro-Russia separatists were the first to reach the crash site. 
 
 “Our self-defense units are already on the site,” said Andrei Purgin, first deputy premier of the breakaway region. “They already reported many dead passengers, including children.” 
 
 Sergei Taruta, the Kiev-appointed governor of the Donetsk region sidelined by the militants, said the separatists were blocking the crash site. 
 
 Russia's RIA Novosti news agency quoted Donetsk separatist leader Oleksandr Boroday as saying the separatists were calling a two- to three-day cease-fire to facilitate investigation of the crash. Boroday was quoted as saying the incident appeared to have been a “provocation.” 
 
 In spite of the conflict in eastern Ukraine, dozens of Europe-to-Asia flights have been passing over the region each day, aviation industry experts say. 
 
 Ukrainian officials had closed airspace below 32,000 feet, an altitude just below that at which the Malaysian jet was flying. 
 
 Mark Duell, vice president of operations at the flight tracking website FlightAware.com, said that flights from carriers that include Transaero Airlines, Emirates Airlines and Singapore Airlines have traveled over the region. 
 
 “We haven't found an airline that's been avoiding it previous to today,” he said. “Of course now that's changed.” 
 
 President Obama said the U.S. government was offering “any assistance we can to help determine what happened and why.” 
 
 Obama learned of the plane's downing while speaking on the phone with Putin on Thursday morning. Putin had requested the call with Obama to discuss the latest round of economic sanctions imposed by Washington and other Western governments. 
 
 News of the plane crash began to break while the two leaders spoke, White House Press Secretary Josh Earnest said later, and Putin mentioned the reports to Obama during the call. 
 
 Malaysian Prime Minister Najib Razak issued a statement lamenting the “terrible and deeply shocking news” of the second loss of a Malaysia Airlines 777 this year. 
 
 On March 8, Flight 370 bound for Beijing went missing, setting off a global search that has riveted international attention. No trace of the flight has been located despite the costliest lost-aircraft search in history.
– Two Ukrainian military fighter jets have been shot down in the east, the country's Defense Ministry is claiming. The Sukhoi-25 fighters were shot down today at 6:30am Eastern (1:30pm local time) over an area called Savur Mogila. Defense Ministry spokesman Oleksiy Dmitrashkovsky says the planes may have been carrying up to two crew members each. The government says the pilots of the planes ejected, though their location and condition are not currently known, reports the Los Angeles Times. CNN notes that the ministry also believes an air defense system shot the planes down. Ukraine is expected to hold a military briefing later today.