Erdogan and Trump discuss 'coordination' in northern Syria as tensions flare

Donald Trump and Recep Tayyip Erdogan have agreed to "more effective coordination" between their countries' military operations in Syria, after Turkey threatened to launch a new offensive against US-backed Kurdish fighters in the war-torn country earlier this week.

The Turkish and United States presidents spoke by telephone on Friday amid heightened tensions between the two NATO countries over their divergent alliances in northern Syria.

On Wednesday, Erdogan announced that Turkey planned to launch a military operation within the "next few days" against the Peoples' Protection Units (YPG), a Kurdish militia allied with Washington in the fight against the Islamic State (IS) group.

A Turkish presidential source said Erdogan and Trump "agreed to ensure more effective cooperation on the subject of Syria" in their call, but did not provide additional details, Reuters and AFP reported.

Ties between Washington and Ankara have been strained in recent years over US support for the YPG.

Ankara considers the group to be an offshoot of the Kurdistan Workers Party (PKK), which has fought a war against the Turkish state since 1984 and is considered a terrorist group by Turkey and its Western allies.

But the YPG has been a key partner in the US fight against IS in Syria, where it has operated under the banner of the Kurdish-led Syrian Democratic Forces (SDF) alliance.

During their phone call, Erdogan told Trump about "Turkey's legitimate security concerns" related to the Kurdish groups allied with the US, AFP reported, citing the Turkish presidential source.

The two leaders "discussed bilateral issues", including security priorities and the fight against terrorism, White House spokeswoman Sarah Huckabee Sanders also told reporters on Friday. "The presidents agreed to continue coordinating to achieve our respective security objectives in Syria," she said.

Turkey prepared to go into Manbij: Erdogan

Speaking to members of the Organisation of Islamic Cooperation in Istanbul earlier on Friday, Erdogan said he was "determined to bring peace and security to areas east of the Euphrates" River in northern Syria.

He said Turkish forces are prepared to enter the Syrian town of Manbij if the US does not remove YPG fighters. Ankara will also target Kurdish-controlled areas farther east, he said.

Now we are saying that you should cleanse, remove them, or else we will enter Manbij. I am speaking very clearly

- Turkish President Recep Tayyip Erdogan

Turkey has complained over the slow implementation of a deal with Washington to pull YPG fighters out of Manbij, which lies in mainly Arab territory west of the Euphrates, back to the eastern bank of the river.

US forces are with the SDF east of the Euphrates, as well as in Manbij.

"Manbij is a place where Arabs live, but they have surrendered the area to the terror organisation," Erdogan said. "Now we are saying that you should cleanse, remove them, or else we will enter Manbij. I am speaking very clearly."

Earlier this week, the Pentagon said any unilateral action by Turkey in northeast Syria was "unacceptable" and cause for concern.

"Unilateral military action into northeast Syria by any party, particularly as US personnel may be present or in the vicinity, is of grave concern. We would find any such actions unacceptable," Commander Sean Robertson, a Pentagon spokesman, said in a statement on Wednesday.

Kurdish commander Mazloum Kobanin, meanwhile, said on Thursday that the SDF would respond strongly to any attack, Reuters reported.