Turkish President Recep Tayyip Erdogan declared Monday that his country was determine to eliminate Kurdish forces from northern Syria if Washington does not persuade them to withdraw from the region. He made his remarks three days after he held a telephone call with US President Donald Trump during which they agreed on “more effective” cooperation on Syria. Turkey may start a new military operation in Syria at any moment, Erdogan said Monday, adding that the White House has responded positively to Ankara’s plans to push into territory where its forces have not previously operated. The Pentagon has expressed grave concern, saying unilateral military action by any party in northeast Syria - where US forces operate - would be “unacceptable”. But Erdogan suggested that Trump was more receptive to Turkish plans to move east of the Euphrates river than his own US Defense Department. “We officially announced that we will start a military operation to the east of the Euphrates, “Erdogan said in a speech in the central province of Konya. “We discussed this with Mr. Trump and he gave a positive response.” Turkey and the United States have long been at odds over Syria policy, where Washington has backed the Syrian Kurdish People’s Protection Units (YPG) against ISIS. Ankara considers the YPG a terrorist organization tied to the Kurdistan Workers Party (PKK), an outlawed group that has waged a three-decade insurgency in southeast Turkey. Erdogan said last week that Ankara would launch a new campaign within days against the YPG, although he has yet to give a more definitive timeline. Any new campaign is likely to be complicated by the presence of US soldiers in northern Syria. Turkey has already intervened to sweep YPG and ISIS from territory west of the Euphrates over the past two years, but has not gone east of the river - partly to avoid direct confrontation with US forces. The Pentagon says it has about 2,000 troops in Syria. “We can start our operations on Syrian soil at any time from locations that suit our planning. Our heroic army has completed its preparations and plans. As I always say, we may come suddenly one night,” Erdogan said on Monday. Erdogan did not elaborate on Trump’s response, but said Turkey would take care to avoid American casualties. Erdogan’s comments appeared to be more conciliatory than those of his interior minister Suleyman Soylu, who earlier accused Washington of attempting to stymie Turkey’s efforts against the YPG over the last two years. “The United States thought it could deter us with the men it has nurtured,” Soylu said during a visit to Pakistan, state-owned news agency Anadolu reported. “Now, they will try to hold us back east of the Euphrates. Turkey did not, and will not, allow that.”