"I think Turkey is very smart... Turkey did an unfriendly takeover, without a lot of lives being lost. I can say that Assad was a butcher, what he did to children," Trump told reporters at his residence in Florida.
Assad fled to Russia after a lightning offensive spearheaded by the Islamist Hayat Tahrir al-Sham (HTS) wrested city after city from his control until the rebels reached the Syrian capital earlier this month.
The collapse of his rule stunned the world and sparked celebrations around Syria and beyond, after his crackdown on protests in 2011 triggered one of the deadliest wars of the century.
Rooted in Syria's branch of Al-Qaeda, HTS is proscribed by several Western governments as a terrorist organization, though it has sought to moderate its rhetoric and pledged to protect the country's religious minorities.
Since the early days of the anti-Assad revolt that erupted in 2011, Turkey has been seen as a key backer of the opposition to his rule.
It has hosted the political opposition, millions of refugees, and also backed rebel groups fighting the army.
Years into the war, HTS took over parts of northwestern Syria, which borders Turkey. It was from there that the organization and allied rebel groups launched the offensive that ousted Assad from power.
Turkey has carried out military strikes inside Syria and has said it is ready to provide armed support to the country's new Islamist-led government set up by the rebels.
Turkish President Recep Tayyip Erdogan's top priority in Syria was to rid the country of Kurdish separatist fighters -- a goal supported by the new government, it has said.
"Turkey is a major force, by the way, and Erdogan is somebody I got along with great," Trump said. "But he has a major military force. And his has not been worn out with war... He's built a very strong, powerful army."
