Turkey and the United States agreed on Friday on “more effective coordination” in operations in Syria, Turkish presidential sources said. Turkish President Recep Tayyip Erdogan and US President Donald Trump held a telephone call shortly after Ankara threatened to launch a new offensive in Syria. The two leaders spoke by telephone and "agreed to ensure more effective cooperation on the subject of Syria", according to the source. The conversation came after Erdogan on Wednesday warned Turkey was planning to launch a new operation within the "next few days" against the US-backed Kurdish Peoples Protection Units (YPG) in northern Syria, reported AFP. Ankara views the YPG as a "terrorist offshoot" of the Kurdistan Workers Party (PKK), which has waged an insurgency against the Turkish state since 1984 and is considered a terror group by Ankara and its Western allies. But the YPG has spearheaded the United States fight against ISIS under the banner of the Kurdish-led Syrian Democratic Forces (SDF) alliance. During their phone call, Erdogan shared with Trump "Turkeys legitimate security concerns caused by the presence and actions of the terrorist organization PKK/PYD/YPG", the source said. Earlier on Friday at a speech in Istanbul, Erdogan said he is "determined to bring peace and security to areas east of the Euphrates" River in Syrias north. Washingtons support of the YPG has strained relations with Turkey over the past couple of years. American forces are with the SDF east of the Euphrates as well as in the flashpoint city of Manbij, which is west of the river. Erdogan has urged the US to drive the YPG out of the city. "Here is what we say: either you clean the city and (the YPG) leave, or were going into Manbij as well," he warned.