In October, Donald Trump threatened to "obliterate" Turkey's economy, and Trump sent Turkish president Recep Tayyip Erdogan a letter on the day the offensive started warning him he could be responsible for "slaughtering thousands of people".
"Don't be a tough guy. Don't be a fool!" Trump wrote.
The letter was released as Trump battled to control political fallout after his decision to withdraw US troops from northern Syria, clearing the way for Turkey's operation against Washington's Kurdish allies.
Erdogan on Wednesday said he returned Trump's Oct. 9th letter.