ANKARA - Turkey said on Monday that the United States made "a fatal mistake" to equate Kurds with the Kurdish militias by warning of economic devastation if Turkey strikes Kurdish forces in Syria during the withdrawal of US troops.

"Turkey is fighting against terrorists rather than Kurds," Turkish Presidential Spokesman Ibrahim Kalin said in tweet.

Turkey will protect Kurds and other Syrians against all terrorist threats, he added.

Turkey regards the People's Protection Units (YPG), which is allied with the United States in the fight against the Islamic State (IS) militant group, as the offshoot of outlawed Kurdistan Workers' Party (PKK) inside Turkey.

Kalin said there was no difference between the IS and the YPG, and Turkey will continue to fight against it.

"Turkey expects the US to honor our strategic partnership and doesn't want it to be shadowed by terrorist propaganda," the Turkish spokesman stressed.

Kalin's response came after US President Donald Trump threatened to target Turkey's economy if Ankara hits Kurds during Washington's withdrawal of troops from Syria.

In mid-December last year, Turkish President Recep Tayyip Erdogan signalled a cross-border operation against Syrian Kurdish militants soon. The operation, however, was postponed after Trump declared the military pullout from Syria.

Since 2016, Turkey has carried out two military operations in northern Syria.