The US says it is stepping aside for an imminent Turkish operation against Kurdish-led forces within Syria that have until now been a key US ally.
Kurdish militias played a major role in defeating the Islamic State IS group, but Turkey regards them as terrorists.
The US, which has hundreds of troops near the Turkey-Syria border, has reportedly begun to withdraw them.
The main Kurdish-led force has condemned the pullout and accused the US of abandoning its fighters.
In January, President Trump threatened to “devastate Turkey economically” if it attacked Kurdish forces.
However, a White House statement issued on Sunday makes no reference to the Kurdish fighters of the YPG.
The statement followed a phone call between President Donald Trump and Turkish President Recep Tayyip Erdogan.
Statement from White House
“Turkey will soon be moving forward with its long-planned operation into northern Syria,” the statement said.
“The United States Armed Forces will not support or be involved in the operation, and United States forces, having defeated the ISIS territorial ‘Caliphate’, will no longer be in the immediate area.”
The White House also said that Turkey would take over all responsibility for IS fighters captured by Kurdish forces over the past two years.
Tens of thousands of former IS fighters, their wives and children are held in Kurdish-run camps in Syria.
The United States government has pressed France, Germany, and other European nations, from which many captured ISIS fighters came, to take them back but they did not want them and refused.
“The United States will not hold them for what could be many years and great cost to the United States taxpayer,” the statement concluded.