Trump's extraordinary warning by Twitter 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 followed 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.