Turkey backed the opposition to Assad in the Syrian civil war that broke out in 2011.

Assad, whose family has been in power for nearly five decades, managed to stay in power thanks to massive Iranian and Russian military support, but large parts of Syria remain outside his reach, including regions in the north, under Turkish control, and in the east, ruled by a US-backed Kurdish-led coalition.

Cavusoglu said he believed US President Donald Trump was considering a policy of leaving Syria.