US President Donald Trump said Monday that he will "obliterate" Turkey's economy if Ankara does anything that in his "great and unmatched wisdom" he considers to be "off limits" in Syria.
Trump's extraordinary Twitter warning against NATO ally Turkey came just after the White House announced a US military drawdown in Turkish-Syrian border areas.
That decision appeared to give Turkey a green light to attack its longtime Kurdish foes, even though they have been fighting alongside US forces against the Islamic State extremist group inside Syria.
Trump's latest tweets appeared to signal a climbdown, following a storm of criticism from his own Republican party that he was betraying the Kurdish guerrillas.
"If Turkey does anything that I, in my great and unmatched wisdom, consider to be off limits, I will totally destroy and obliterate the Economy of Turkey (I've done before!)," he wrote.
The diplomatic and political turmoil first erupted late Sunday when the White House announced that it was removing troops in the Syria-Turkey border area and that "Turkey will soon be moving forward with its long-planned operation into Northern Syria."
That came shortly after a phone call between Trump and his Turkish counterpart Recep Tayyip Erdogan, who has long wanted to target the Kurdish militias operating in Syria.
Until now that had been impossible because they were working closely with US troops against ISIS, a campaign that Trump says is now completed.
Trump appeared to have miscalculated regarding the ferocity of the response from his own party.
A top ally, US Senator Lindsey Graham, warned that Turkey would face sanctions if it invades Syria -- and in a rare message of defiance against Trump he tweeted that the sanctions would get "veto-proof" support in Congress