The United States has pledged to stop supplying weapons to a Kurdish militia in Syria, Turkey said on Saturday, calling on Washington to immediately remove its troops from a Syrian town of Manbij that Turkish forces plan to target.

Turkey's air and ground offensive in northwest Syria's Afrin region against the Kurdish YPG militia has opened a new front in the seven-year, multi-sided Syrian civil war and strained ties with NATO ally Washington.

Ankara views the YPG as terrorists and as an extension of the outlawed Kurdistan Workers Party (PKK) and has been infuriated by U.S. support, including arms and training, for the militia. The Kurdish fighters have played a prominent role in U.S.-led efforts to combat the hardline Islamic State in Syria.

Since the start of the eight-day-old incursion, dubbed"Operation Olive Branch" by Ankara, President Tayyip Erdogan has said Turkish forces would push east towards the town of Manbij, potentially putting them in confrontation with U.S. troops deployed there.

U.S. National Security Adviser H.R. McMaster told Erdogan's spokesman, Ibrahim Kalin, in a telephone call that the United States would no longer provide weapons to the YPG, the Turkish presidency said on Saturday.

"It was emphasised that Turkey's legitimate security concerns must be paid attention to. It was agreed that close coordination would be carried out in order to avoid misunderstandings," it said.

The agreement is likely to be seen by Ankara as a substantial diplomatic victory from the incursion, where Turkish troops and their Syrian rebel allies appear to have made modest advances, as heavy rain and poor weather have hampered air strikes and progress on the ground.

Turkey's foreign minister said the United States needed to follow up its promise with concrete action, including the immediate withdrawal of its troops from the vicinity of Manbij.

"The United States needs to break its link with (the) terrorist organisation and make them drop their weapons completely. They need to collect the weapons they gave, they need to withdraw from Manbij immediately," Mevlut Cavusoglu told reporters on Saturday.

The U.S. State Department did not immediately respond to requests for comment about ending arms to the YPG or exiting Manbij.

Erdogan said this week that Turkish forces would sweep Kurdish fighters from the length of Syrian border and could push all the way east to the frontier with Iraq, a move that would risk a possible confrontation with U.S. forces allied to the Kurds.

Any drive by Turkish forces toward Manbij, part of Kurdish-held territory some 100 km (60 miles) east of Afrin, could also threaten U.S. efforts to stabilise northern Syria. The United States has about 2,000 troops in Syria, officially as part of the international coalition against Islamic State.

U.S. forces were deployed in and around Manbij to deter Turkish and U.S.-backed rebels from attacking each other and have also carried out training missions in the area.

A senior official for the U.S.-backed Syrian Democratic Forces (SDF), an alliance of Syrian fighters spearheaded by the Kurdish YPG, said any wider Turkish assault would face an"appropriate response".

Redur Xelil also said in an interview that he was sure the U.S.-led coalition against Islamic State, which has backed the SDF in its battle against the jihadists, was trying to put pressure on Turkey to limit its offensive.

Turkey and its Free Syrian Army (FSA) rebel allies have killed a total of 394 militants since the incursion began, Erdogan said on Saturday. Turkey and the FSA rebel factions have together lost 20 people he said, without giving a breakdown.

Later on Saturday, the Turkish military said that two soldiers and two FSA fighters had been killed and another 11 soldiers and four FSA fighters had been lightly wounded in clashes on Saturday.

In a statement, the military also said 447 militants had been "neutralised" since the operation had started, with 57 of those on Saturday.

The SDF has accused Turkey of exaggerating the number of Kurdish fighters it has killed.

The Syrian Observatory for Human Rights, a Britain-based war monitoring group, said that 36 civilians in Afrin, including 10 children, have died so far.

A total of 59 YPG fighters and at least 69 fighters from the Turkey-backed FSA have died in clashes, the Observatory said. Seven Turkish soldiers have been killed and another seven are missing, it said.</s>ANKARA/BEIRUT (Reuters) - President Tayyip Erdogan said on Sunday that Turkey will “clean” its entire border with Syria in a sign that the Turkish offensive on the Syrian Kurdish YPG group in northern Syria’s Afrin region could be extended further.

Since Turkey’s assault in Afrin began nine days ago, it has increased tensions between Ankara and the United States, which has supported the YPG in other parts of Syria in the fight against Islamic State.

“Step by step, we will clean our entire border,” Erdogan said in a speech after the army said it had captured Jebel Bursaya, a hill that Turkish media had described as a critical position in recent days.

Erdogan said last week that Turkey might conduct operations eastwards inside Syria all the way to Iraq to clear the YPG from its frontier. Syrian Kurdish officials have pledged to meet any wider Turkish assault with an “appropriate response”.

More than a week into their offensive, however, Turkey and allied Syrian rebel groups have made only modest progress fighting into hilly terrain against entrenched foes.

The U.S.-backed Syrian Democratic Forces, an alliance of militias of which the YPG is the strongest, had said earlier on Sunday that there was intense fighting in the area.

A war monitor, the Syrian Observatory for Human Rights, said Turkey and its allied rebel groups had taken the hill, which overlooks the major Syrian town of Azaz, which they also hold.

The Observatory said Turkish air strikes had killed three people in one family early on Sunday in Afrin. Turkish bombardment also damaged an ancient temple, it said.</s>Turkey on Sunday stepped up its offensive against Kurdish militia in Syria for a ninth, in a campaign that has strained relations with the United States.

After several days of poor visibility because of heavy rain and fog, Turkish warplanes and artillery took advantage of the clear skies and pounded the hill of Barsaya near the Kurdish town of Afrin in northwestern Syria, official news agency Anadolu said.

Turkey launched operation "Olive Branch" on January 20 against the Syrian Kurdish People's Protection Units (YPG) in Afrin, supporting Syrian opposition fighters with ground troops and air strikes.

While Turkey brands the YPG a "terror" group, the militia has received support from the US, its fighters spearheading the battle against the Islamic State group across swathes of Syria.

Despite souring relations with NATO ally Washington, President Recep Tayyip Erdogan has threatened to expand the offensive against the YPG to Manbij, east of Afrin.

And in a sign the Turkish campaign has rendered prospects for peace in Syria even fainter, authorities in the war-torn country's Kurdish autonomous region said they will not attend peace talks in Russia's Sochi.

"We said before that if the situation remained the same in Afrin we could not attend Sochi," regional official Fawza al-Yussef said.

Rebel backer Turkey is one of the sponsors of the talks in the Black Sea resort on Monday and Tuesday, along with Damascus allies Russia and Iran.

Turkey's air and artillery strikes on Sunday were even fiercer than previous days, said an AFP correspondent on the Syrian-Turkish border who saw towers of smoke rising into the sky.

Turkish channel NTV broadcast live footage Sunday showing rocket fire targeting Barsaya hill, located to the north of Afrin, near the strategic border town of Azaz.

"I spoke earlier with a commander who said: 'With God's help, we will take over Barsaya very soon,'" Erdogan said in a speech in Corum in northern Turkey.

Turkish troops and their Syrian opposition allies said Monday they had captured the hill, before losing it again a few hours later.

Sunday's battles "are very fierce on Barsaya ... which is strategic because it overlooks Azaz on the Syrian side and Kilis on the Turkish side", Syrian Observatory for Human Rights director Rami Abdel Rahman told AFP.

"Today's clashes are more intense," he added.

Turkish relations with the US have dipped over their stances on the YPG -- which Ankara says is a "terrorist" offshoot of the outlawed Kurdistan Workers' Party (PKK).

The PKK, which has waged a war against the Turkish state for three decades, is proscribed as a terror group by Ankara and its Western allies.

US President Trump earlier this week urged Erdogan to "de-escalate" his forces assault on Afrin as he expressed concern about "the destructive and false" anti-American rhetoric emanating from Turkey.

Adding fuel to the fire, Turkey's Foreign Minister Mevlut Cavusoglu on Saturday urged the US to "immediately withdraw" its personnel from Kurdish-held Manbij, which Ankara has also threatened to attack.

"We are going to cleanse Manbij" after Afrin, government spokesman Bekir Bozdag said Sunday, according to Anadolu.

Manbij was retaken from IS by the Kurdish-led Syrian Democratic Forces in 2016 as part of a push that would later recapture the city of Raqa from the jihadists.

Faced with the Turkish onslaught, the YPG's political arm the Kurdish Democratic Union Party (PYD) appealed to the international community to pressure Ankara into halting its offensive.

Five Turkish soldiers have died since "Olive Branch" was launched, while around 40 others have been injured.

One soldier who was killed Saturday will be laid to rest later Sunday in Istanbul.

The fighting has also led to a heavy loss of civilian lives.

According to the Britain-based Observatory, 42 civilians have been killed since January 20, including 12 children, most of them in Turkish air strikes.

In a sign of the sheer ferocity of the fighting, 69 pro-Turkish rebels were killed, as were 66 Kurdish fighters.

Earlier this month, the US-led coalition fighting IS said it was working to create a 30,000-strong border security force in northern Syria, which would include the YPG.

Several nations, including Germany and France, as well as the European Union, have expressed concern over the Turkish offensive against a country where over 340,000 people have already been killed since war erupted in 2011.</s>The Syrian Democratic Forces have downed a Turkish helicopter in the Syrian city of Afrin, an SDF representative told Sputnik Saturday.Earlier this day, the SDF reported that the group's militia had downed two Turkish reconnaissance Unmanned Aerial Vehicles (UAV) in the village of Adama, northern Syria.The group also engaged in skirmishes with a Turkish convoy in the Chia district of Afrin and with Turkish forces, supported by the Free Syrian Army, in Qastal Ma'af.Kurdish militia has downed two Turkish reconnaissance Unmanned Aerial Vehicles (UAV) in the village of Adama, northern Syria, the Syrian Democratic Forces' (SDF) media center reported Saturday.Beyond that, the media center stated that the SDF also attacked a Turkish military convoy in the Chia district, killing two Turkish soldiers.According to the report, Turkey continues to bomb Afrin, especially the districts of Jabal Bafalon and Chia. The SDF, in their turn, are repelling the attacks of the Turkish forces, supported by the Free Syrian Army, on Qastal Ma'af, which is a strategically important point, and have managed to destroy an armored vehicle.Turkey has been conducting the Olive Branch military operation in the Kurdish-dominated Syrian town of Afrin since January 20. The town is controlled by the US-backed Kurdish People's Protection Units (YPG), which is considered to be affiliated with the Kurdistan Workers' Party (PKK), designated as a terrorist group by Turkey and several other countries. According to Ankara, the offensive is not aimed against the Syrian government; the latter, however, described the operation as a violation of Syria's sovereignty.</s>Ankara: President Tayyip Erdogan said on Sunday that Turkey will "clean" its entire border with Syria in a sign that the Turkish offensive on the Syrian Kurdish YPG group in northern Syria`s Afrin region could be extended further.

Since Turkey`s assault in Afrin began nine days ago, it has increased tensions between Ankara and the United States, which has supported the YPG in other parts of Syria in the fight against Islamic State.

"Step by step, we will clean our entire border," Erdogan said in a speech after the army said it had captured Jebel Bursaya, a hill that Turkish media had described as a critical position in recent days.

Erdogan said last week that Turkey might conduct operations eastwards inside Syria all the way to Iraq to clear the YPG from its frontier. Syrian Kurdish officials have pledged to meet any wider Turkish assault with an "appropriate response".

More than a week into their offensive, however, Turkey and allied Syrian rebel groups have made only modest progress fighting into hilly terrain against entrenched foes.

The U.S.-backed Syrian Democratic Forces, an alliance of militias of which the YPG is the strongest, had said earlier on Sunday that there was intense fighting in the area.

A war monitor, the Syrian Observatory for Human Rights, said Turkey and its allied rebel groups had taken the hill, which overlooks the major Syrian town of Azaz, which they also hold.

The Observatory said Turkish air strikes had killed three people in one family early on Sunday in Afrin. Turkish bombardment also damaged an ancient temple, it said.</s>ANKARA/BEIRUT, Jan 27 (Reuters) - The United States has pledged to stop supplying weapons to a Kurdish militia in Syria, Turkey said on Saturday, calling on Washington to immediately remove its troops from a Syrian town of Manbij that Turkish forces plan to target.

Turkey's air and ground offensive in northwest Syria's Afrin region against the Kurdish YPG militia has opened a new front in the seven-year, multi-sided Syrian civil war and strained ties with NATO ally Washington.

Ankara views the YPG as terrorists and as an extension of the outlawed Kurdistan Workers Party (PKK) and has been infuriated by U.S. support, including arms and training, for the militia. The Kurdish fighters have played a prominent role in U.S.-led efforts to combat the hardline Islamic State in Syria.

Since the start of the eight-day-old incursion, dubbed "Operation Olive Branch" by Ankara, President Tayyip Erdogan has said Turkish forces would push east towards the town of Manbij, potentially putting them in confrontation with U.S. troops deployed there.

U.S. National Security Adviser H.R. McMaster told Erdogan's spokesman, Ibrahim Kalin, in a telephone call that the United States would no longer provide weapons to the YPG, the Turkish presidency said on Saturday.

"It was emphasised that Turkey's legitimate security concerns must be paid attention to. It was agreed that close coordination would be carried out in order to avoid misunderstandings," it said.

The agreement is likely to be seen by Ankara as a substantial diplomatic victory from the incursion, where Turkish troops and their Syrian rebel allies appear to have made modest advances, as heavy rain and poor weather have hampered air strikes and progress on the ground.

Turkey's foreign minister said the United States needed to follow up its promise with concrete action, including the immediate withdrawal of its troops from the vicinity of Manbij.

"The United States needs to break its link with (the) terrorist organisation and make them drop their weapons completely. They need to collect the weapons they gave, they need to withdraw from Manbij immediately," Mevlut Cavusoglu told reporters on Saturday.

The U.S. State Department did not immediately respond to requests for comment about ending arms to the YPG or exiting Manbij.

Erdogan said this week that Turkish forces would sweep Kurdish fighters from the length of Syrian border and could push all the way east to the frontier with Iraq, a move that would risk a possible confrontation with U.S. forces allied to the Kurds.

Any drive by Turkish forces toward Manbij, part of Kurdish-held territory some 100 km (60 miles) east of Afrin, could also threaten U.S. efforts to stabilise northern Syria. The United States has about 2,000 troops in Syria, officially as part of the international coalition against Islamic State.

U.S. forces were deployed in and around Manbij to deter Turkish and U.S.-backed rebels from attacking each other and have also carried out training missions in the area.

A senior official for the U.S.-backed Syrian Democratic Forces (SDF), an alliance of Syrian fighters spearheaded by the Kurdish YPG, said any wider Turkish assault would face an "appropriate response".

Redur Xelil also said in an interview that he was sure the U.S.-led coalition against Islamic State, which has backed the SDF in its battle against the jihadists, was trying to put pressure on Turkey to limit its offensive.

Turkey and its Free Syrian Army (FSA) rebel allies have killed a total of 394 militants since the incursion began, Erdogan said on Saturday. Turkey and the FSA rebel factions have together lost 20 people he said, without giving a breakdown.

The SDF has accused Turkey of exaggerating the number of Kurdish fighters it had killed.

The Syrian Observatory for Human Rights, a Britain-based war monitoring group, said that 36 civilians in Afrin, including 10 children, have died so far.

A total of 59 YPG fighters and at least 69 fighters from the Turkey-backed FSA have died in clashed, the Observatory said. Seven Turkish soldiers have been killed and another seven are missing, it said. (Additional reporting by Yeganeh Torbati in Washington; Writing by David Dolan and Louise Heavens)</s>Turkish-backed Syrian rebels, wearing red ribbons, raise a rebel flag as they stand alongside Turkish soldiers on a mountain on the Syrian-Turkish border, north of Azaz, on Sunday (AFP photo)

HASSA, Turkey — Turkey on Sunday stepped up its offensive against Kurdish militia in Syria for a ninth day, in a campaign that has strained relations with the United States.

After several days of poor visibility because of heavy rain and fog, Turkish warplanes and artillery took advantage of the clear skies and pounded the hill of Barsaya near the Kurdish town of Afrin in northwestern Syria, official news agency Anadolu said.

Turkey launched operation “Olive Branch” on January 20 against the Syrian Kurdish People’s Protection Units (YPG) in Afrin, supporting Syrian opposition fighters with ground troops and air strikes.

While Turkey brands the YPG a “terror” group, the militia has received support from the US, its fighters spearheading the battle against the Daesh terror group across swathes of Syria.

Despite souring relations with NATO ally Washington, President Recep Tayyip Erdogan has threatened to expand the offensive against the YPG to Manbij, east of Afrin.

And in a sign the Turkish campaign has rendered prospects for peace in Syria even fainter, authorities in the war-torn country’s Kurdish autonomous region said they will not attend peace talks in Russia’s Sochi.

“We said before that if the situation remained the same in Afrin we could not attend Sochi,” regional official Fawza Al Yussef said.

Rebel backer Turkey is one of the sponsors of the talks in the Black Sea resort on Monday and Tuesday, along with Damascus allies Russia and Iran.

Turkey’s air and artillery strikes on Sunday were even fiercer than previous days, said an AFP correspondent on the Syrian-Turkish border who saw towers of smoke rising into the sky.

Turkish channel NTV broadcast live footage Sunday showing rocket fire targeting Barsaya hill, located to the north of Afrin, near the strategic border town of Azaz.

“I spoke earlier with a commander who said: ‘With God’s help, we will take over Barsaya very soon,’” Erdogan said in a speech in Corum in northern Turkey.

Turkish troops and their Syrian opposition allies said Monday they had captured the hill, before losing it again a few hours later.

Sunday’s battles “are very fierce on Barsaya ... which is strategic because it overlooks Azaz on the Syrian side and Kilis on the Turkish side”, Syrian Observatory for Human Rights Director Rami Abdel Rahman told AFP.

“Today’s clashes are more intense,” he added.

Turkish relations with the US have dipped over their stances on the YPG — which Ankara says is a “terrorist” offshoot of the outlawed Kurdistan Workers’ Party (PKK).

The PKK, which has waged a war against the Turkish state for three decades, is proscribed as a terror group by Ankara and its Western allies.

US President Trump earlier this week urged Erdogan to “de-escalate” his forces assault on Afrin as he expressed concern about “the destructive and false” anti-American rhetoric emanating from Turkey.

Adding fuel to the fire, Turkey’s Foreign Minister Mevlut Cavusoglu on Saturday urged the US to “immediately withdraw” its personnel from Kurdish-held Manbij, which Ankara has also threatened to attack.

“We are going to cleanse Manbij” after Afrin, government spokesman Bekir Bozdag said Sunday, according to Anadolu.

Manbij was retaken from Daesh by the Kurdish-led Syrian Democratic Forces in 2016 as part of a push that would later recapture the city of Raqqa from the extremists.

Faced with the Turkish onslaught, the YPG’s political arm the Kurdish Democratic Union Party (PYD) appealed to the international community to pressure Ankara into halting its offensive.

Five Turkish soldiers have died since “Olive Branch” was launched, while around 40 others have been injured.

One soldier who was killed Saturday will be laid to rest later Sunday in Istanbul.

The fighting has also led to a heavy loss of civilian lives.

According to the Britain-based observatory, 42 civilians have been killed since January 20, including 12 children, most of them in Turkish air strikes.

In a sign of the sheer ferocity of the fighting, 69 pro-Turkish rebels were killed, as were 66 Kurdish fighters.

Earlier this month, the US-led coalition fighting Daesh said it was working to create a 30,000-strong border security force in northern Syria, which would include the YPG.

Several nations, including Germany and France, as well as the European Union, have expressed concern over the Turkish offensive against a country where over 340,000 people have already been killed since war erupted in 2011.</s>ANKARA, Jan 27 (Reuters) - The United States has told Turkey it will not provide any more weapons to the Syrian Kurdish YPG militia, the Turkish presidency said on Saturday, as Turkey's offensive against the U.S.-backed YPG in Syria entered its eighth day.

The Turkish incursion in northwest Syria's Afrin region against the YPG has opened a new front in the multi-sided Syrian civil war, but has also further strained ties with NATO ally Washington.

Washington has angered Ankara by providing arms, training and air support to the Syrian Kurdish forces. Turkey sees the YPG as an extension of the outlawed Kurdistan Workers Party (PKK), which has waged a deadly insurgency in Turkey's largely Kurdish southeast for three decades.

The Turkish presidency said in a statement on Saturday that Ibrahim Kalin, spokesman for President Tayyip Erdogan, and U.S. National Security Adviser H.R. McMaster held a phone call on Friday in which McMaster confirmed the United States would no longer provide weapons to the YPG.

On Thursday, the Pentagon said it carefully tracked weapons provided to the YPG and would continue discussions with Turkey, after Ankara urged Washington to end its support for the YPG or risk confronting Turkish forces on the ground in Syria.

On Friday, Erdogan said Turkish forces would sweep Kurdish fighters from the Syrian border and could push all the way east to the frontier with Iraq - a move which risks a possible confrontation with U.S. forces allied to the Kurds.

Since the start of the incursion, dubbed "Operation Olive Branch" by Ankara, Erdogan has said Turkish forces would push east towards the town of Manbij, part of Kurdish-held territory some 100 km (60 miles) east of Afrin, where U.S. troops were deployed to deter Turkish and U.S.-backed rebels from clashing.

Any Turkish advance towards Manbij could threaten U.S. efforts to stabilise northern Syria, where the United States has about 2,000 troops, officially as part of the international coalition against Islamic State.

In a sign of growing bilateral tensions, Ankara and Washington disagreed over the main message of a phone call between Erdogan and U.S. President Donald Trump held on Wednesday.

The White House said Trump had urged Erdogan to curtail the military operation in Syria, while Turkey said Erdogan had told Trump that U.S. troops should withdraw from Manbij.

Pentagon spokeswoman Dana White said she had seen media reports about the phone call, but was not aware of any change in U.S. posture.

The Turkish presidency said Kalin and McMaster had agreed for Turkey and the United States to remain in close coordination to "avoid misunderstandings". (Reporting by Tuvan Gumrukcu; Editing by Mark Potter)</s>ANKARA (Reuters) - The United States has told Turkey it will not provide any more weapons to the Syrian Kurdish YPG militia, the Turkish presidency said on Saturday, as Turkey’s offensive against the U.S.-backed YPG in Syria entered its eighth day.

The Turkish incursion in northwest Syria’s Afrin region against the YPG has opened a new front in the multi-sided Syrian civil war, but has also further strained ties with NATO ally Washington.

Washington has angered Ankara by providing arms, training and air support to the Syrian Kurdish forces. Turkey sees the YPG as an extension of the outlawed Kurdistan Workers Party (PKK), which has waged a deadly insurgency in Turkey’s largely Kurdish southeast for three decades.

The Turkish presidency said in a statement on Saturday that Ibrahim Kalin, spokesman for President Tayyip Erdogan, and U.S. National Security Adviser H.R. McMaster held a phone call on Friday in which McMaster confirmed the United States would no longer provide weapons to the YPG.

On Thursday, the Pentagon said it carefully tracked weapons provided to the YPG and would continue discussions with Turkey, after Ankara urged Washington to end its support for the YPG or risk confronting Turkish forces on the ground in Syria.

On Friday, Erdogan said Turkish forces would sweep Kurdish fighters from the Syrian border and could push all the way east to the frontier with Iraq - a move which risks a possible confrontation with U.S. forces allied to the Kurds.

Since the start of the incursion, dubbed “Operation Olive Branch” by Ankara, Erdogan has said Turkish forces would push east towards the town of Manbij, part of Kurdish-held territory some 100 km (60 miles) east of Afrin, where U.S. troops were deployed to deter Turkish and U.S.-backed rebels from clashing.

Any Turkish advance towards Manbij could threaten U.S. efforts to stabilise northern Syria, where the United States has about 2,000 troops, officially as part of the international coalition against Islamic State.

In a sign of growing bilateral tensions, Ankara and Washington disagreed over the main message of a phone call between Erdogan and U.S. President Donald Trump held on Wednesday.

The White House said Trump had urged Erdogan to curtail the military operation in Syria, while Turkey said Erdogan had told Trump that U.S. troops should withdraw from Manbij.

Pentagon spokeswoman Dana White said she had seen media reports about the phone call, but was not aware of any change in U.S. posture.

The Turkish presidency said Kalin and McMaster had agreed for Turkey and the United States to remain in close coordination to “avoid misunderstandings”.</s>Turkey says the United States has agreed to stop providing weapons to the Kurdish YPG militia, as Ankara enters its eight day of an offensive against the Syrian minority.

The United States has pledged to stop supplying weapons to Kurdish militia in Syria, Turkey says, calling on Washington to immediately remove its troops from a Syrian town of Manbij that Turkish forces plan to target next.

US National Security Adviser HR McMaster told Turkish President Tayyip Erdogan spokesman, Ibrahim Kalin, that the United States would no longer provide weapons to the Kurdish YPG militia, the Turkish presidency said.

Turkey's air and ground offensive in northwest Syria's Afrin region against the Kurdish YPG militia has opened a new front in the seven-year, multi-sided Syrian civil war and strained ties with NATO ally Washington.

Ankara views the YPG as terrorists and as an extension of the outlawed Kurdistan Workers Party (PKK) and has been infuriated by US support, including arms and training, for the militia.

Kurdish fighters have played a prominent role in US-led efforts to combat the hard-line Islamic State in Syria.

When Turkey launched their attack on the city of Afrin last week, Kurdish forces called on their US ally for help, while NATO ally Turkey warned against US involvement.

"The US and international community have a moral obligation to stand behind the Kurdish people now," YPG forces said in a statement as the offensive began.

Just prior to the launch of the eight-day-old incursion, dubbed "Operation Olive Branch" by Ankara, Mr Erdogan criticised the US for arming the Kurds, saying, "this is not what allies do".

Mr Erdogan said he hoped the US "would not give rise to error by appearing on the same side as the terror organisation".

Guney Yildiz — Syria and Kurdish specialist for the European Council for foreign Relations — told the ABC Turkey chose to begin its attack with Afrin because the US does not have airspace control or troops in that area.

But Mr Erdogan's announcement of plans to attack Manbij, where the US do have troops, and to then push right through to the Iraqi border was a "challenge the US position", Mr Yildiz said.

Earlier in the week, the White House warned that the campaign risked exacerbating a humanitarian crisis and disrupting what had been a stable area.

"We urge Turkey to exercise restraint in its military actions and rhetoric, ensure that its operations are limited in scope and duration, ensure humanitarian aid continues and avoid civilian casualties," White House spokeswoman Sarah Sanders said in a briefing.

The agreement to stop supplying weapons is likely to be seen by Ankara as a substantial diplomatic victory from the incursion, where Turkish troops and their Syrian rebel allies appear to have made modest advances.

Turkey's foreign minister said the United States needed to follow up its promise with concrete action, including the immediate withdrawal of its troops from the vicinity of Manbij.

"They need to collect the weapons they gave, they need to withdraw from Manbij immediately."

The United States has about 2,000 troops in Syria, officially as part of the international coalition against Islamic State.
According to the Turkish presidency, United States National Security Advisor H. R. McMaster said January 26 that the U.S. "will not provide any more weapons to the Syrian Kurdish YPG militia".