An excerpt from the book by Washington Post journalist Bob Woodward,said that the US president told Defense Secretary James Mattis that he intended to assassinate the Syrian leader, after Washington accused the government in Damascus of a suspected chemical weapons attack against the terrorist-held village of Khan Shaykhun in Syria's Northwestern Province of Idlib last year.

"Let's … kill him! Let's go in. Let's kill the … lot of them," Trump told Mattis on the phone.

Mattis reportedly told Trump he would get "right on it" in an apparent attempt to pacify the president, but hung up the phone and instead told a senior aide, "We're not going to do any of that. We're going to be much more measured," Woodward wrote.

The US national security team then prepared a plan for a more conventional airstrike that Trump ultimately ordered.

The Washington Post journalist also said the defense secretary had marveled at the time at Trump's ignorance on foreign affairs and told close associates the US president had the intelligence of "a fifth- or sixth-grader."

On April 4, 2017, a suspected sarin gas attack hit the town of Khan Shaykhun in Syria’s Idlib Province, killing more than 80 people.

The Western countries rushed to blame the incident on Damascus, with the US launching a missile attack against Shayrat Airbase in Syria’s Homs Province on April 7, 2017.

Trump tweeted a day later that the military attack against Syrian targets was a “Mission Accomplished!”