Trump's hasty announcement in December of a US exit from the war-torn country has caused confusion among allies and adversaries alike, and it also led to the resignation of Defense Secretary James Mattis.
Maria Zakharova, a Russian Foreign Ministry spokeswoman, said it was important for Syrian Kurds and the Syrian government to start talking to each other in light of the U.S. withdrawal plans.
His top diplomat Mike Pompeo is on a whirlwind regional tour aimed at reassuring Washington's Kurdish allies in the fight against Isis.
Last week, Turkish President Recep Tayyip Erdoğan publicly lashed out at USA national security adviser John Bolton for saying the United States withdrawal was contingent upon Turkey's pledge not to attack US-backed Kurdish fighters in Syria once troops leave.
President Trump used Twitter Sunday night to spell out his plans for a pull-out in Syria.
The previous week, Trump's National Security Advisor John Bolton had announced that Washington would withdraw its troops from Syria only after defeating ISIS and ensuring that the Kurds are safe.More news: Chelsea 'want Callum Hudson-Odoi buy-back clause'
"Will devastate Turkey economically if they hit Kurds", Trump said on Twitter, suggesting that there would be a 20-mile safe zone around the group after USA forces leave.
"We find correct his statement about the removal of the elements that concern Turkey", Foreign Minister Mevlut Cavusoglu said in a speech in the southern Turkish province of Antalya. Without giving any further details, he wrote "Create 20 mile (32 kilometers) safe zone".
Islamic State militants are "living their final moments" in the last enclave they hold near the Iraqi border, where USA -backed Syrian Democratic Forces (SDF) are attacking them, an SDF official said on Sunday.
Relations between the two North Atlantic Treaty Organisation allies have been strained over U.S. backing for the Kurdish YPG, which Turkey views as an extension of the outlawed Kurdistan Workers Party (PKK) waging a decades-long insurgency on Turkish soil.
The Kurds have sought Russian meditation for the talks with President Bashar al-Assad's government, part of their strategy to fill a vacuum that will be left when U.S. forces withdraw.
"We recognize the Turkish people's right and President Erdogan's to defend their country from terrorists", Pompeo said Saturday, according to NPR's Michele Kelemen, who is traveling with the secretary. "Will attack [ISIS] again from existing nearby base if it reforms".
"The U.S.is withdrawing from northeast Syria in a strong, deliberate and coordinated manner, and seeks to ensure that the forces that have fought alongside coalition partners in the campaign against ISIS are not mistreated", an administration official said following the president's tweet. "Stop the ENDLESS WARS!"