U.S. National Security Adviser John Bolton was meeting with his Turkish counterpart Ibrahim Kalin on Tuesday, days after Bolton added a condition to the U.S. withdrawal, saying Turkey must agree to protect the United States' "Kurdish ally.”

President Donald Trump said last month he was bringing home the some U.S. 2,000 troops in Syria, saying they had succeeded in their mission to defeat the Islamic State (IS). His abrupt move sparked concern among officials in Washington and allies abroad and prompted Defence Secretary Jim Mattis to resign.

"Give them or destroy them," a Hurriyet newspaper headline said, referring to what it said were 22 U.S. military bases in Syria. It cited unspecified sources as saying Turkey would not accept Washington handing them over to the YPG.

A senior Turkish security official told Reuters last week Washington needed to allow Turkey to use its bases in Syria.

With tensions simmering over Trump's Syria strategy, it was unclear if Bolton would meet with President Tayyip Erdogan.

Also in Bolton's delegation were U.S. Chairman of the Joint Chiefs of Staff General Joseph Dunford and U.S. special Syria envoy James Jeffrey.

Erdogan warned on Monday the U.S. withdrawal must be planned carefully and with the right partners, saying only Turkey had "the power and commitment to perform that task".

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