HASSA, Turkey (AP) — Turkish troops and Syrian opposition forces attacked a Kurdish enclave in northern Syria on Sunday in their bid to oust from the area a U.S.-allied Kurdish militia, which responded with a hail of rockets on Turkish towns killing at least one refugee.

The Turkish offensive on Afrin, codenamed Operation Olive Branch, started Saturday and has heightened tensions in the already complicated Syrian conflict, threatening to further strain ties between NATO allies Turkey and the United States.

On Sunday, the United States urged Turkey to exercise restraint and ensure that the offensive is "limited in scope and duration." A statement by State Department spokeswoman Heather Nauert also asked Turkey to be "scrupulous to avoid civilian casualties," adding that all parties involved in Syria should focus on defeating the Islamic State group.

The Syrian government, Iran and Egypt condemned the attack, which activists said has killed at least 18 civilians in the Kurdish-held enclave, Afrin, in the first 24 hours. Turkish officials say 11 rockets launched from Syria have landed in Turkish towns along the border, killing at least one Syrian refugee and injuring 47.

France called for an emergency U.N. Security Council meeting to discuss the developments there and urged Turkish authorities "to act with restraint in a context where the humanitarian situation is deteriorating in several regions of Syria."

Turkish officials said the troops entered Afrin a day after dozens of Turkish jets and artillery units at the border pounded Syrian Kurdish targets. A spokesman for the Kurdish fighters said the attack was repelled.

Turkey considers the Syrian Kurdish militia, known as the People's Protection Units, or YPG, a terror organization and a security threat because of its affiliation with Kurdish rebels fighting in southeastern Turkey.

The group controls Afrin, in Syria's northwestern Aleppo province, as well as nearly 25 percent of Syrian territory, to the east along Turkey's border. The YPG also forms the backbone of the Syrian Democratic Forces, the main U.S. ally against the Islamic State group in Syria.

U.S. support for the Kurdish militia has been a cause of perpetual conflict between Ankara and Washington, which has backed the Kurdish militia.

U.S. officials have said that the administration had appealed to Turkey not to go ahead with the offensive. A Turkish operation there could have an impact on U.S. operations further east in Syria, the officials said.

The operation, for which Turkey has also rallied nearly 10,000 Syrian opposition fighters, could spill into a wider Turkish-Kurdish confrontation inside Turkey. There is an estimated 8,000 to 10,000 Kurdish fighters in the Afrin district, the Turkish prime minister said.

The operation also includes airstrikes on the district, threatening to create another humanitarian disaster in the region. The Afrin district houses no less than 800,000 civilians, including displaced people from earlier years of the Syrian war. Russia pulled back troops that had been deployed near Afrin after it was briefed on the operation by Turkey.

Kurdish officials said Russian military officials have proposed handing over Afrin to the Syrian government to avert a Turkey military offensive. They said they refused the proposal.

Badran Ciya Kurd, an adviser to the Kurdish administration in northern Syria who meets regularly with Russian and US officials, told The Associated Press Sunday that Russian officials suggested that handing over the enclave, encircled by Syrian government and its rival Turkey and Syrian fighters it backs, would avert the Turkish offensive.

It was not immediately possible to reach Russian officials.

Prime Minister Binali Yildirim told a group of journalists that Turkey aims to create a 30-kilometer (20-mile) deep "secure zone" in Afrin.

On Sunday, the state-run Anadolu Agency said the Turkish-backed fighters had penetrated 5 kilometers (3 miles) into Afrin as part of the offensive. At least one person, a Syrian refugee in Turkey, was killed when Reyhanli, a Turkish border town, came under a hail of rockets Sunday.

It was the second Turkish town to come under attack. Earlier, the rockets fired from Syria targeted the border town of Kilis, but there were no casualties.

In a statement, the Syrian opposition fighters battling alongside the Turkish troops said the combined force seized Shinkal, a village on the northwestern edge of Afrin district. A Syrian rebel commander said the clashes with the YPG fighters were intense, but that the Turkey-backed forces would fight to "eliminate terrorism" from the area.

SDF spokesman Mustafa Bali denied that Turkish troops had entered Afrin, saying Kurdish forces have been repelling attacks since Saturday. Bali said the SDF sent reinforcements to Afrin. The YPG said meanwhile that it had destroyed two Turkish tanks.

The Britain-based Syrian Observatory for Human Rights said that Kurdish militia and Turkish forces clashed on the northern and western edges of Afrin. It said the Turkey-backed forces entered Shinkal and Adah Manli to the west. It added that the Turkey-backed forces captured three YPG fighters. The Observatory said airstrikes killed eight in Afrin's southeast, bringing the total of civilians killed since the attack began to 18.

Sepan Jan, a journalist in Afrin, said stores and services were operating normally. Residents in border villages were taking precautions against the bombings, he said. The only road out of Afrin, leading to government-controlled Aleppo, has been closed for security reasons, he added.

Turkish President Recep Tayyip Erdogan has vowed to expand the offensive to Manbij, a town to the east that Kurdish forces seized from IS in a costly battle with the aid of the U.S.-led coalition. The town has since emerged as a model for U.S.-backed Kurdish rule of largely Arab areas.

A Turkish dvance on Manbij would further strains relations with Washington, which has troops operating in the Manbij area.

Turkish troops first crossed into Syria after the Kurds captured Manbij in 2016, in part to prevent them from expanding westward and linking territory to Afrin. At least 70 Turkish soldiers were killed, most in battles with IS militants, which have since been driven from nearly all the territory it once held in Syria.

Syria's government had vowed to shoot down any Turkish fighter jets over Afrin, calling it an "aggressive act." On Sunday, President Bashar Assad condemned the "brutal aggression" on Afrin but didn't repeat the threat. He said Turkey has always supported "terrorists" in Syria.

Iran, a close ally of Assad, also condemned the Turkish assault and called on Turkey to end it.

"The continuing crisis in Afrin may boost terrorist groups again in the northern parts of Syria," Iranian Foreign Ministry spokesman Bahram Ghasemi said according to Iran's official IRNA news agency.

Egypt, which maintains security coordination with Syria and is at odds with Turkey, said the military offensive threatened political negotiations.

Turkey has prepared around 10,000 Syrian fighters to storm Afrin, according Rami Abdurrahman, director of the Syrian Observatory for Human Rights. Some were stationed in Azaz, on the eastern edge of Afrin and others in Atmeh to the south.

El Deeb reported from Beirut. Associated Press writer Suzan Fraser in Ankara, Turkey contributed to this report.

Copyright 2017 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.</s>Turkey said it had begun a ground incursion into the Kurdish enclave in Syria known as Afrin on Sunday, a day after intense aerial bombardment that signalled the opening of hostilities in a new phase of Ankara’s involvement in the war across the border.

The launch of the ground campaign by the Turkish military, alongside Syrian rebel factions under Ankara’s tutelage, came on the second day of a military offensive called “Operation Olive Branch” by the Turkish government, with dozens of airstrikes hitting more than 150 targets in the Kurdish-dominated district from late on Saturday afternoon.

Kurdish militias shelled the Turkish province of Kilis across the border in response.

A spokesman for the Kurdish militias that control the district said they had blocked the Turkish army-led initial attempt at a ground incursion on Sunday morning.

“The Turkish army and its Syrian agent factions have not entered one inch of Afrin district inside Syria,” the spokesman claimed.

Turkey says it is launching the Afrin campaign to clear out the People’s Protection Units (YPG) and its political arm, the PYD, from the district. Ankara regards them as part of the Syrian wing of the Kurdistan Workers’ party (PKK), a designated terror group that has fought a decades-long insurgency against the Turkish state.

Ankara has been angered by the YPG’s expansion in northern Syria and its alliance with the anti-Islamic State US-led coalition, which has backed and later armed the group as it spearheaded offensives against Isis in the region. The Afrin offensive came after a US announcement that it would train an army to patrol Syria’s borders that includes the YPG as a key component, which Turkey said was a national security threat.

Turkey intervened in the war in Syria in August 2016 to limit Kurdish expansion west of the Euphrates river and to drive Isis, which controlled key border towns, from the area as well. The Afrin offensive was launched after Ankara apparently obtained Russia’s blessing, dispatching its chief of intelligence and army’s chief of staff to Moscow in recent days.

It takes place against a backdrop of deep-seated tensions with Washington and continuing military losses for the Turkey-backed opposition in Syria, where Bashar al-Assad has inched closer to a military victory in the seven-year conflict, and peace talks brokered by Russia, Turkey and Iran have gone nowhere.

Turkey sought to couch its military offensive as being both linked to the YPG’s presence in the area but also as a measure to protect the local populace from what an official described as an “authoritarian” group and almost as a nation-building exercise.

But the move has provoked fierce debate within Syria’s opposition, which has enjoyed broad Turkish backing for years. Some see it as a diversion from a campaign by the Syrian government against Idlib, the last province under rebel control, describing the Syrian rebel factions taking part in the offensive as mercenaries to Turkey’s will.

Others see the offensive as a necessary measure against the YPG, which they accuse of attempting to carve out a statelet in northern Syria, displacing local Arabs and which they believe to be secretly in league with the Assad regime.

Turkish officials pledged to pursue a campaign with limited civilian casualties, but said they believed the Kurdish militias would use human shields to protect key installations. A spokesman for the PYD, the political arm of the Kurdish militias, said Turkish airstrikes had killed six civilians on Saturday and wounded 13 others, in addition to killing three fighters from the YPG and its auxiliary female militia, the YPJ.

“The Turkish army wants through these military operations to inspire fear among civilians to force them from their lands and lay the ground for occupying the city,” the YPG branch in Afrin said in a statement, adding that it held both Ankara and Moscow accountable for the “massacres that will be committed in Afrin”.</s>HASSA, Turkey (AP) — Turkish troops and Syrian opposition forces attacked a Kurdish enclave in northern Syria on Sunday in their bid to drive a U.S.-allied Kurdish militia from the region.

Turkish officials said the troops entered the enclave of Afrin a day after dozens of Turkish jets and Turkish artillery units at the border pounded Syrian Kurdish targets as part of an offensive, codenamed Olive Branch, that came on the heels of sharp threats from Turkey's leaders.

Turkey considers the Syrian Kurdish militia, known as the People's Protection Units, or YPG, a terror organization and a security threat because of its affiliation to Kurdish rebels fighting in southeastern Turkey.

The group controls Afrin, in Syria's northwestern corner, as well as a swath of territory along Turkey's border. The YPG also forms the backbone of the Syrian Democratic Forces, the main U.S. ally against the Islamic State group in Syria.

SDF spokesman Mustafa Bali denied that Turkish troops had entered Afrin, saying Kurdish forces had been repelling attacks since Saturday.

The Britain-based Syrian Observatory for Human Rights says the Kurdish militia and Turkish forces have clashed on the northern and western edges of Afrin, but that Turkish troops have failed to advance.

Turkish President Recep Tayyip Erdogan has promised to expand the operation to other Kurdish regions. Turkish media reports have quoted Prime Minister Binali Yildirim as telling a group of journalists on Sunday that Turkey aims to create a 30-kilometer (20-mile) deep "secure zone" in Afrin.

Earlier Sunday, four rockets fired from Syria hit the Turkish border town of Kilis, prompting Turkish artillery to return fire, Gov. Mehmet Tekinarslan said. The rockets hit two offices and office building, and slightly wounded one person.

The state-run Anadolu Agency said the Turkish-backed fighters had penetrated 5 kilometers (3 miles) into Afrin.

Associated Press journalists on the border saw a convoy of trucks, believed to belong to Syrian opposition fighters, carrying pick-up trucks mounted with arms. Artillery shelling could be heard in the distance.

Turkey has prepared around 10,000 Syrian fighters to storm Afrin, according Rami Abdurrahman, director of the Syrian Observatory for Human Rights, a Britain-based monitoring group.

A Syrian commander speaking to the AP by phone from northern Syria said there were thousands of fighters positioned in Azaz, at the frontier with the Kurdish enclave, awaiting orders. Another commander said hundreds more were stationed in Atmeh, south of Afrin. The officials spoke on condition of anonymity because they were not authorized to speak to the media.

Turkish leaders were infuriated by an announcement by the U.S. military this week that it was going to create a 30,000-strong border force with the Kurdish fighters to secure northern Syria. Days later, Secretary of State Rex Tillerson announced that the U.S. would maintain a military presence with the Kurds for the foreseeable future.

Associated Press writer Suzan Fraser in Ankara, Turkey contributed to this report.

Copyright 2017 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.</s>16:31 21.01.2018(updated 17:39 21.01.2018)Get short URLIran has called on Turkey to end its offensive in Syria's Afrin as it may help terrorists in the region, state news agency IRNA reported Sunday."Iran hopes that this operation will be ended immediately to prevent a deepening of the crisis in the border regions of Turkey and Syria. A continued crisis in Afrin may boost…terrorist groups in northern Syria," the agency quoted Foreign Ministry spokesman Bahram Qasemi as saying.The Egyptian Foreign Ministry, in its turn, issued a statement, saying that the ongoing Turkish military operation was a "disruption" of the political settlement of the Syrian crisis."The Arab Republic of Egypt expresses its rejection of the military operation carried out by the Turkish troops against the town of Afrin in northwestern Syria, considering the operation as yet another violation of Syria's sovereignty and the disruption of efforts within the framework of the existing political decisions and efforts on struggle against terrorism in Syria," the statement said.The ministry said that Cairo strongly opposed the military solution to the Syrian crisis calling for a comprehensive political process.Earlier today, NTV broadcaster reported that Turkish tanks entered Syrian Afrin , backing the offensive of the Free Syrian Army (FSA) armed opposition group on the positions of Kurdish militia.The announcement came a day after the Turkish General Staff had declared the launch of the operation dubbed Olive Branch against the Kurdish forces in Afrin. The operation started at 14:00 GMT and over 70 Turkish warplanes conducted airstrikes in seven districts of Afrin, where 108 targets out of 113 were destroyed. The military operation has already been condemned by Damascus with the Syrian Foreign Ministry calling the act a violation of Syrian sovereignty.</s>"Syria: Ghouta, Idlib Afrin — France has requested an urgent meeting of UN Security Council," Le Drian said on Twitter after talks with his Turkish counterpart.

The minister further continued, saying that the parties should stop the fire immediately and provide a complete humanitarian access.

Earlier today, NTV broadcaster reported that Turkish tanks entered Syrian Afrin, backing the offensive of the Free Syrian Army (FSA) armed opposition group on the positions of Kurdish militia.

The announcement came a day after the Turkish General Staff had declared the launch of the operation dubbed Olive Branch against the Kurdish forces in Afrin. The operation started at 14:00 GMT and over 70 Turkish warplanes conducted airstrikes in seven districts of Afrin, where 108 targets out of 113 were destroyed. The military operation has already been condemned by Damascus with the Syrian Foreign Ministry calling the act a violation of Syrian sovereignty.

A spokesman for the Kurdish People's Protection Units (YPG) in Afrin, however, denied Turkish claims that its forces had entered the district.</s>AIN ISSA, Syria (Reuters) - The U.S.-backed, Kurdish-led Syrian Democratic Forces (SDF) group said on Monday it was studying whether to send reinforcements to the Afrin region of Syria to help fend off a Turkish attack.

Turkey launched a cross-border attack on Saturday on the frontier region of Afrin, saying its aim is to crush the YPG, a Syrian Kurdish militia that has been the principal military ally of the United States on the ground against Islamic State.

The YPG militia is the biggest part of the U.S.-backed SDF, which also includes Arab fighters. The YPG said that more fighters would be sent to Afrin if necessary but the area was already well reinforced in anticipation of a Turkish attack.

“We are in the framework of looking at the possibility of sending more military forces to Afrin,” SDF spokesman Kino Gabriel said in a televised news conference, calling for international efforts to halt the Turkish attack.

YPG spokesman Nouri Mahmoud, speaking to Reuters on the sidelines of the news conference, said: “Our forces prepared themselves and were betting on an attack by the current authority in Turkey.”

The SDF and the YPG control a swathe of northern and eastern Syria in addition to the Afrin region in the northwest.

The United States has backed them with air strikes, arms, training and 2,000 troops on the ground, infuriating Turkey which considers the YPG to be allies of Kurdish insurgents that have battled the Turkish state for decades.

Sending any reinforcements to Afrin from SDF-held areas further east would appear to require SDF fighters to pass through territory near Aleppo held by the government of President Bashar al-Assad, complicating the journey in a country where a multi-sided civil war is entering its eighth year.

U.S. special forces do not operate in Afrin. The U.S.-led military coalition has told its Syrian allies that it was working politically to halt the Turkish attack, the SDF spokesman said.

An SDF statement vowed that Afrin would be a “quagmire from which the Turkish army will only exit after suffering great losses” and called on the coalition to meet its responsibility towards “our forces and our people in Afrin”.

The Turkish assault on Afrin opens a new front in a war in which world powers have supported rival sides, while hundreds of thousands of people have died and more than 11 million have been driven from their homes.

Mahmoud, the YPG spokesman, accused Russia -- major military backer of Assad’s government -- of giving permission to Turkey to fly its warplanes over Afrin. Russia withdrew its own forces from the region ahead of the attack. The SDF said Russia had switched off its radars.

President Tayyip Erdogan said on Monday that Turkey had an agreement with Russia regarding its military operation against the YPG in Afrin and that Ankara would not take a step back from the operation.</s>Turkey says it has launched a much-awaited air and ground offensive against the Kurdish-controlled enclave of Afrin in northern Syria.

After days of shelling, Turkish fighter jets on Saturday carried out air raids on the border district targeting positions held by the Syrian Kurdish PYD and YPG groups.

The heavy bombardment began as units of pro-Ankara rebels known as the Free Syrian Army (FSA) started moving into Afrin, according to the state-run Anadolu news agency.

Turkish President Recep Tayyip Erdogan said on Saturday that the operation in Afrin would be followed by a push in the northern town of Manbij, which the US-backed Kurdish forces captured from ISIL in 2016.

Turkey considers Syria’s Kurdish Democratic Union Party (PYD) and its armed wing, the YPG, “terrorist groups” with ties to the banned Kurdistan Workers’ Party (PKK), which has waged a decades-long fight inside Turkey.

The US has previously armed the YPG, viewing it as the most effective ground force in its fight against the Islamic State of Iraq and the Levant (ISIL, also known as ISIS) armed group.

Erdogan said that all Kurdish armed groups “are all the same” and that changing their names “does not change the fact that they are terror organisations”.

According to estimates, there are between 8,000 to 10,000 Kurdish fighters in the Afrin area.

 ‘Complicated situation’

Al Jazeera’s Stefanie Dekker, reporting from Antakya in Turkey, said the launch of the operation followed a week of “increasingly strong political rhetoric” coming from Turkish officials.

“The Turkish army says it is only targeting what it calls ‘terrorists’ … and not civilians – but certainly it will be terrifying for civilians in that area because they are surrounded,” she added.

“To highlight the complexity of this war, there is now a NATO ally, Turkey, bombing a group that the US calls its best ally when it was fighting ISIL on the ground and still continues to do so – so it’s an incredibly complicated situation.”

In recent days, Ankara has been repeatedly threatening to crush the Syrian Kurdish fighters.

 WATCH: Syria – Kurdish civilians fear threat of Turkey offensive (2:09)

On Friday, Turkey’s Defence Minister Nurettin Canikli said his country would go ahead with its military offensive in Afrin, saying Syrian Kurdish fighters there pose a “real” threat to his country.

Ankara fears the establishment of a Kurdish corridor along its border and had been deploying troops and tanks there in preparation for the ground assault.

“We will wipe out this corridor step-by-step, starting from the west,” Erdogan said on Saturday. “Afrin operation has de facto started in the field. This will be followed by Manbij.”

Syria had earlier warned against any operation and said it would shoot down Turkish fighter jets.

 Ground push

On Friday, Turkey mobilised thousands of FSA rebels to Hatay province near the Syrian border, as part of the planned offensive.

Anadolu reported that the FSA rebels were taken “under extensive security” in a convoy of at least 20 buses, from the province of Kilis.

Last year, Turkey launched Operation Euphrates Shield, in which Turkish-backed FSA rebels cleared a large part of northern Syria of armed fighters.

“The language coming from the Turks has been that the Afrin operation is going to be the start, then they are going to move into Manbij and then all the way to the Iraqi border,” said Dekker.

“Manbij is a town west of the Euphrates, the YPG remains there and Turkey always wanted the YPG to move east of the Euphrates. The last time there was a confrontation there between the two sides the Americans moved in with troops and vehicles to calm that down.”

 Syrian Kurds rally on Thursday against the Turkish threats in Afrin, Aleppo province [AP]

Following the start of Turkey’s air campaign, the defence ministry of Russia, which controls the airspace over Afrin, said it was pulling back soldiers that had been deployed near the city.

It said in a statement that “to prevent possible provocations, to exclude the threat to life and health of Russian servicemen, the operational group of the Center for Reconciliation of warring parties and military police in the Afrin area is relocated to the Tell-Adjar area”.

Moscow’s military intervention in Syria in 2015 turned the war in favour of Syrian President Bashar al-Assad.

“It’s now clear that the Russians have given tacit green light to this [Turkish operation] because they control the airspace – so seeing Turkey flying air sorties means the Russians have agreed to this.”

“However, we have also heard from the Russians that they are concerned that they are watching it closely and that they urge constraint.”

This came as Turkish officials reportedly had discussions with US and Russian officials, as well as a rare official contact with Assad’s government.

 WATCH: Turkish air raids target Kurdish fighters in Iraq and Syria (1:52)

Meanwhile, Stephane Dujarric, spokesman of UN Secretary-General Antonio Guterres, warned against more military activities in Syria.

“We’ve seen the reports of shelling in Afrin. We reiterate our call on all concerned parties to avoid further escalation and any acts that could deepen the suffering of the Syrian people,” Dujarric said.

“All parties must ensure protection of civilians at all times, under any circumstances.”

The US had also urged Turkey to avoid taking action against the Kurdish rebels, urging Ankara to keep its focus on ISIL.

There have been reports that the US was also trying to recruit Kurdish fighters in Syria to fight against ISIL.

In response, Turkey warned that its relations with the US would be “irreversibly harmed” if Washington moves to form the 30,000-strong army in the north of Syria.</s>HASSA, Turkey (AP) - Turkish troops and Syrian opposition forces attacked a Kurdish enclave in northern Syria on Sunday in their bid to drive a U.S.-allied Kurdish militia from the region.

Turkish officials said the troops entered the enclave of Afrin a day after dozens of Turkish jets and Turkish artillery units at the border pounded Syrian Kurdish targets as part of an offensive, codenamed Olive Branch, that came on the heels of sharp threats from Turkey's leaders.

Turkey considers the Syrian Kurdish militia, known as the People's Protection Units, or YPG, a terror organization and a security threat because of its affiliation to Kurdish rebels fighting in southeastern Turkey.

The group controls Afrin, in Syria's northwestern corner, as well as a swath of territory along Turkey's border. The YPG also forms the backbone of the Syrian Democratic Forces, the main U.S. ally against the Islamic State group in Syria.

SDF spokesman Mustafa Bali denied that Turkish troops had entered Afrin, saying Kurdish forces had been repelling attacks since Saturday.

The Britain-based Syrian Observatory for Human Rights says the Kurdish militia and Turkish forces have clashed on the northern and western edges of Afrin, but that Turkish troops have failed to advance.

Turkish President Recep Tayyip Erdogan has promised to expand the operation to other Kurdish regions. Turkish media reports have quoted Prime Minister Binali Yildirim as telling a group of journalists on Sunday that Turkey aims to create a 30-kilometer (20-mile) deep "secure zone" in Afrin.

Earlier Sunday, four rockets fired from Syria hit the Turkish border town of Kilis, prompting Turkish artillery to return fire, Gov. Mehmet Tekinarslan said. The rockets hit two offices and office building, and slightly wounded one person.

The state-run Anadolu Agency said the Turkish-backed fighters had penetrated 5 kilometers (3 miles) into Afrin.

Associated Press journalists on the border saw a convoy of trucks, believed to belong to Syrian opposition fighters, carrying pick-up trucks mounted with arms. Artillery shelling could be heard in the distance.

Turkey has prepared around 10,000 Syrian fighters to storm Afrin, according Rami Abdurrahman, director of the Syrian Observatory for Human Rights, a Britain-based monitoring group.

A Syrian commander speaking to the AP by phone from northern Syria said there were thousands of fighters positioned in Azaz, at the frontier with the Kurdish enclave, awaiting orders. Another commander said hundreds more were stationed in Atmeh, south of Afrin. The officials spoke on condition of anonymity because they were not authorized to speak to the media.

Turkish leaders were infuriated by an announcement by the U.S. military this week that it was going to create a 30,000-strong border force with the Kurdish fighters to secure northern Syria. Days later, Secretary of State Rex Tillerson announced that the U.S. would maintain a military presence with the Kurds for the foreseeable future.

Associated Press writer Suzan Fraser in Ankara, Turkey contributed to this report.</s>Direct military action against territory held by Kurdish militia opens a new front in Syria’s civil war and sees Ankara confronting Kurds allied to the United States at a time when Turkey’s relations with Washington are reaching breaking point.

Turkey’s army said earlier it had hit shelters and hideouts used by militants from three groups - the Kurdistan Workers’ Party (PKK), PYD and YPG, after militants fired on Turkish positions inside Turkey.

The Free Syrian Army has also started to support the Turkish military in Afrin, the official said.

Turkish President Tayyip Erdogan said earlier on Saturday that a military operation in the Afrin region had begun after cross-border shelling by the Turkish army.</s>By Mehmet Guzel and Philip Issa, The Associated Press

KOCABEYLI, Turkey — Turkish jets bombed the Kurdish-controlled city of Afrin in northern Syria on Saturday, as President Recep Tayyip Erdogan promised to expand Turkey’s military border operations against a Kurdish group that has been the U.S.’s key Syria ally in the war on the Islamic State group.

The raids came on the heels of a week of sharp threats by the Turkish government, promising to clear the Kurdish People’s Protection Units, or YPG, from Afrin and its surrounding countryside, also called Afrin. Turkey’s military is calling the campaign Operation Olive Branch.

Turkey says the YPG — a group it considers a terrorist organization — is an extension of an outlawed Kurdish rebel group that it is fighting inside its own borders, and it has found common cause with Syrian opposition groups who view the YPG as a counter-revolutionary force in Syria’s multi-sided civil war.

Turkish Prime Minister Binali Yildirim said a ground offensive could begin Sunday, but the state run Anadolu News Agency reported that Syrian forces backed by Ankara had already penetrated the Kurdish enclave. They crossed over from Turkey but were turned back by the YPG, according to Rojhat Roj, a Kurdish spokesman.

Associated Press journalists at the Turkish border saw jets bombing positions in the direction of Afrin, as a convoy of armed pickup trucks and buses believed to be carrying Syrian opposition fighters traveled along the border. Video from Turkey this week showed the military moving tanks to the frontier.

Roads out of the Afrin were closed and the YPG were not allowing anyone to leave the city, but morale was high, according to a resident who was reached by phone.

“So far the People’s Protection Units have not called on the people to mobilize,” said Ramzi Hamidi. Turkey, he said, “will learn a lesson they have not learned before.”

Ten civilians were wounded in the airstrikes, three seriously, according to Roj.

Turkey has prepared around 10,000 Syrian fighters to storm Afrin, according Rami Abudrrahman, director of the Syrian Observatory for Human Rights monitoring group. A rebel commander speaking to the AP by phone from north Syria said there were thousands of fighters positioned in Azaz, at the frontier with the Kurdish enclave, awaiting orders. Another commander said hundreds more were stationed in Atmeh, south of Afrin. The officials spoke on the condition of anonymity because they were not authorized to speak to the media.

The Russian Defense Ministry said, meanwhile, that it was pulling back troops that had been deployed near Afrin, two days after Turkey’s military and intelligence briefs travelled to Moscow to discuss the planned operation. It said the group of observers was being relocated to another area. It was not immediately clear how many troops were affected by the move.

The YPG is the driving force behind a coalition of north Syrian forces allied with the U.S. to battle the Islamic State group. With U.S. support, including around 2,000 embedded forces, the coalition now controls close to a quarter of Syrian territory, concentrated mostly to the north and east of the Euphrates River.

Turkish leaders were infuriated by an announcement by the U.S. military six days ago that it was going to create a 30,000-strong border force with the Kurdish fighters to secure northern Syria. Days later, Secretary of State Rex Tillerson announced that the U.S. would maintain a military presence with the Kurds for the foreseeable future.

Tillerson spoke by phone with Russian Foreign Minister Sergey Lavrov and Turkish Foreign Minister Mevlut Cavusoglu, the U.S. State Department said. No details about the calls were immediately available, but the State Department has previously said it’s urging against escalation.

Speaking in the city of Kutahya in western Turkey, Erdogan announced an expansion to Turkish operations in Syria, promising to move on the Kurdish-controlled town of Manbij and its surrounding countryside after completing operations in Afrin. The operation would force out the Kurdish militia from all positions west of the Euphrates River.

In 2016, Turkey trained and equipped opposition forces to drive Kurdish fighters out of parts of north Syria, driving a wedge between two enclaves along the Turkish frontier. Turkish ground forces, including tanks and artillery, crossed into Syria with the fighters to establish a zone flanked by Afrin and Manbij that now serves as hub for Turkish operations inside the war-torn country.

Turkish Prime Minister Binali Yildirim said the strikes on Afrin marked the start of a campaign to “eliminate the PYD and PKK and Daesh elements in Afrin,” referring to the Kurdish Democratic Union Party and the Kurdistan Worker’s Party respectively, and using an Arabic acronym for the Islamic State group.

The PYD, PKK, and YPG all look to the Kurdish Marxist-nationalist leader Abdullah Ocalan as their guide. Ocalan is imprisoned by Turkey for waging a separatist movement in the eastern part of the country. The IS group does not have a presence in Afrin.

The air strikes were accompanied by waves of artillery strikes on the Afrin region. Syria’s Foreign Ministry promptly condemned the Turkish operation.

Turkish Foreign Minister Mevlut Cavusoglu discussed the operation with Tillerson by phone on Sunday after the U.S. diplomat requested a conversation, Turkish officials said. They did not provide further details.

Any ground operation would entail considerable military and political risk for Ankara. Russia was keeping military observers in Afrin and lately firmed up its ties with the YPG, while Syria’s government in Damascus said it would shoot down any Turkish jets on raids in the country. The YPG is estimated to have between 8,000 and 10,000 fighters in Afrin. Turkey could also face blowback from the Kurdish insurgency within its own borders.

A ground offensive or continued shelling would exacerbate the poor humanitarian situation in Afrin, which is now home to at least 800,000 civilians, including many who arrived fleeing the fighting in other parts of Syria.

Also on Saturday, Syrian government forces and supporting militias retook a key air base in northwest Syria lost to rebels in 2015.

Syria’s state broadcaster said Syrian troops fought their way into the strategic Abu Zuhour air base in Idlib province.

It was a coup for the government and allied militias who advanced swiftly to take the base in what was considered a stronghold for rebels and al-Qaida insurgents.

But the advance, which began in earnest in late December, has displaced more than 200,000 civilians, according to the U.N., exacerbating an already dire humanitarian situation in the north of the country.

Issa reported from Beirut. Associated Press writers Suzan Fraser in Ankara, Turkey, and Bassem Mroue in Aleppo, Syria contributed to this report.
Turkish President Erdoğan announces that Turkish Army ground troops have entered the district of Afrin in Syria. Turkish Prime Minister Binali Yıldırım says the goal is to establish a 30-km safe zone.