In an op-ed article for the New York Times, a day before he was due to meet US National Security Adviser John Bolton, Erdogan said Turkey was committed to defeating Islamic State and "other terrorist groups" in Syria.
The US President said: "We have defeated Isis in Syria, my only reason for being there during the Trump Presidency".
A top White House aide says US troops won't leave northeastern Syria until Islamic State militants are defeated and USA -allied Kurdish fighters are protected.
Bolton said his meetings with Turkish officials, including Erdogan, would seek to clarify uncertainty around Turkey's "objectives and capabilities" in Syria. "I never said we were doing it quickly".
"Part of what we want to see is no vacuum in northeast Syria that malign forces can take advantage of, so that will be a big part of discussions with the Turks", Bolton said.
"Turkey constitutes a bigger threat to Kurdish existence than Daesh and all global terrorist organizations", he said, using the Arabic acronym for the Islamic State group.
US National Security Advisor John Bolton, Joint Chiefs of Staff Gen. Joseph F. Dunford Jr. and James Jeffrey, a US special representative for Syria and the anti-Daesh coalition, will hold talks with Turkish officials in Ankara.
On a December visit to a US air base in Iraq, Trump said that military commanders had repeatedly requested extensions for the 2,000 USA troops in Syria - requests that he finally turned down because he said Islamic State was largely beaten. PKK is the outlawed Kurdistan Workers' Party. Either we will never withdraw from "northeastern Syria", or we will stand by and watch our anti-ISIS allies get massacred as Turkey reneges on any security pledge they make.
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Trump, speaking to journalists before departing the White House for Camp David on Sunday, denied there was any walk-back of his December announcement. He also said that Washington is "determined" to keep it that way because the two nations need a "strong bond" and "strong leadership" in increasingly tumultuous times for security.
Asked if a USA pullout would be halted if Turkey could not guarantee the Kurdish fighters would be safe, Bolton said: "Basically, that's right".
Bolton maintained there is no fixed timetable for completing the drawdown, but insisted it was not an indefinite commitment to the region.
The US visit comes amid anger in Turkey over comments by Secretary of State Mike Pompeo, in which he said the US wanted to prevent Turkey "slaughtering" Kurds in Syria.
Although the United States does not recognize Israeli control over the Golan Heights, it voted for the first time in November against an annual U.N. resolution condemning the Israeli position, hinting at a possible shift in USA policy.
Meanwhile, America's Kurdish allies in north-east Syria were left feeling exposed as Turkey, which regards them as terrorists, appeared poised to move against them.
While Trump has expressed confidence that Turkey, which controls its own Syrian force opposed to the Kurds and to President Bashar Assad, is capable of picking up the remaining fight against the Islamic State, Pentagon and State Department officials question Turkish priorities and capabilities.
Russian Federation and Iran back Syrian President Bashar al-Assad.