Trump said Turkey and Syria must keep the peace.
"It's their neighborhood. They need to take care of it," Trump said. "Let someone else fight over this long bloodstained sand."
The president said a small number of troops would remain in Syria to protect oil interests.
Wednesday morning, Trump tweeted there was "Big success on the Turkey/Syria border."
"Safe Zone created! Ceasefire has held and combat missions have ended," Trump tweeted.
Turkey and Russia reached an agreement Tuesday, installing their forces along the border of northeast Syria after U.S. troops that were withdrawn from the area, The Associated Press reported.
On Tuesday, Russian President Vladimir Putin and Turkish President Recep Tayyip Erdogan met in Sochi, Russia, and revealed a 10-point memorandum about Syria, CNN reported. According to the memorandum, Turkish military and Russian military police will patrol the border. The United States was not included in the negotiations.