Donald Trump's plan to "take out" Assad will be aired in the next instalment of the BBC's "Trump Takes on the World" documentary this week.
In episode two of the three-parter, attention turns from the former US leader's run-ins with European leaders to those in the Middle-East.
And in the show, deputy national security adviser K.T. McFarland recalls Trump's reaction when civilian casualties were reported in Syria when Assad unleashed chemical warfare.
She tells viewers the conversation went like: "I wanna take him out!” “Well, Mr President,” she explained, “you can’t do that, it’s an act of war.”
Another adviser, John Bolton, also adds that the former leader almost retaliated to Iran shooting down a military drone until someone pleaded with him not to.
Mr Bolton added: "It’s not the outcome of the chaotic decision-making, it’s the chaotic decision-making."
And Irish viewers can watch this and many other parts of the programme when it airs on BBC Two on Wednesday night at 9pm.
In the first episode, now available online, the leader's relationship with European leaders was examined and a missed interaction with Vladimir Putin was one that really caught viewers.
A furious Trump exploded in rage at his White House aides during the "toe-curling" moment - and would not let the matter go.
"Trump at this point looks not orange, but red," jokes Fiona McLeod Hill, former Downing Street Chief of Staff.
"He flipped, furious. He said, 'You’re telling me Vladimir Putin called the White House and you’re only telling me now during this lunch?'.
"Honestly you could feel the tumbleweed just completely take over the entire lunch table and my toes were curling."
At this point, it is reported that inconsolable Trump dropped his shoulders, looked at Mrs May and said: "I don't believe this.
"Vladimir Putin is the only man in the world who can destroy the United States and I didn’t take his call."
According to Shannon, Trump suddenly realised he was "playing out" in front of the British delegation and the Prime Minister.
"It was a unseemly moment in the early days of his administration so he changed the subject," explains Shannon.
Trump asked Mrs May what her position on climate change was, and she was halfway through saying she is an ardent fan of conversation when she was rudely interrupted.
Suddenly Trump stopped, turned to National Security Advisor Michael Flynn and said: "You're telling me that VP called the White House and you didn't tell me?"
The former US President was still fuming with his team when he spoke to then French President François Hollande the following day.
Watch this and many other parts of the show when it airs on BBC Two on Wednesday night at 9pm.
