US Secretary of Defense Mark Esper said in a written statement: "Despite the opposition and repeated warnings from the United States and the international community, Turkish President Erdogan ordered a unilateral invasion of northern Syria that has resulted in widespread casualties, refugees, destruction, insecurity, and a growing threat to U.S. military forces."

Esper added: "This unacceptable incursion has also undermined the successful multinational "Defeat ISIS" mission in Syria, and resulted in the release of many dangerous ISIS detainees."

The Secretary of Defence continued: "Due to Turkey's irresponsible actions, the risk to U.S. forces in northeast Syria has reached an unacceptable level.  We are also at risk of being engulfed in a broader conflict.  Therefore, at the President's direction, the Department of Defense is executing a deliberate withdrawal of U.S. military personnel from northeast Syria."

Esper insisted that "Turkey's unilateral action was unnecessary and impulsive. The bilateral relationship between our two countries has also been damaged." 

Esper said he will be visiting NATO next week in Brussels, where "I plan to press our other NATO allies to take collective and individual diplomatic and economic measures in response to these egregious Turkish actions."