Kurdish forces have begun pulling back from the Turkish border area of northeast Syria, local Kurdish authorities said on Tuesday after a deal between Washington and Ankara to create a buffer zone. They said work began on Saturday for "the first practical steps — in the Ras Al Ain area — in removing some earth mounds and withdrawing a group of [Kurdish] People's Protection Units and heavy weapons". On Monday, they repeated the steps in Tal Abyad, "showing the seriousness of our commitment to current understandings" on the buffer zone, the semi-autonomous Kurdish administration said. The so-called "safe zone" agreed to by the United States and Turkey this month aims to create a buffer on the border with Syrian areas controlled by the Kurdish People's Protection Units or YPG, a group Ankara sees as "terrorists". Details of the safe zone are hazy, and no final date has been set for when it would be established. But on Monday, Turkey's President Recep Tayyip Erdogan said Turkish troops would soon enter northeast Syria. "Our armed drones, drones and helicopters are in the region," he said. "We expect our ground troops to enter the region very soon," he told supporters in eastern Turkey. On Saturday, Turkish Defence Minister Hulusi Akar said a US-Turkey operations centre aimed at creating the buffer area was at "full capacity". He said the first joint helicopter flight took place on Saturday afternoon. Mazlum Abdi, the chief of the Kurdish-led Syrian Democratic Forces, on Saturday said his forces would support the implementation of the US-Turkey deal. Turkey has repeatedly threatened to attack Kurdish-held areas in northeast Syria. Ankara considers the YPG, which forms the backbone of the SDF, to be an extension the outlawed Kurdistan Workers' Party or PKK — a group that has fought a bloody insurgency inside Turkey for 35 years. The "safe zone" was initially suggested by Washington to dissuade Ankara from carrying out another cross-border attack, after previous offensives in 2016 and last year. The YPG has been a key partner to Washington in the fight against ISIS in Syria. But as the fight against ISIS winds down in the region, the prospect of a US military withdrawal has stoked Kurdish fears of another Turkish attack. Syria's Kurds have largely stayed out of the country's eight-year civil war, instead building their own autonomous institutions in areas they control.