Washington DC officials had told opposite numbers in London to expect the president to order surgical strikes on Syrian regime targets.
President Trump also started telling members of Congress that he was considering military action in Syria.
He had already told America that the dawn attack on Tuesday morning that killed at least 86 people - including 27 children - “crossed a lot of lines for me”.
12
A source said it's a good opportunity to show 'he's different to Obama'Credit: AP:Associated Press
12
DC officials have told opposite numbers in London to expect the president to order surgical cruise missiles strikesCredit: EPA
12
Trump is hoping to send a message to North Korea to halt its nuclear weapons programmeCredit: Reuters
Before launching the Tomahawk missile strike, Trump declared “something should happen” to derail Syrian despot Bashar al-Assad’s regime.
He added: “What Assad did is terrible.”
US Secretary of State Rex Tillerson said “steps were under way” to organise an international coalition to oust Assad.
A senior government source told The Sun: “Trump’s people are clear that he wants to do this, and we think he will.
“He thinks it’s a good opportunity to show people he’s different from Obama, and North Korea will also see that.”
After initially refusing to say whether she would back Trump's military action, Prime Minister Theresa May's government has said the missile strike was an appropriate response to Assad's depraved chemical attack.
12
The nerve gas massacre killed at least 86 people - including 27 children
12
Horrific images show piles of dead children after the attack
12
Shocking images show the destruction at a hospital in Khan Sheikhun, Idlib, following the atrocity
12
Theresa May has backed Trump's missile strike in SyriaCredit: EPA
May branded the Sarin slaughter “a despicable attack” adding: “All those who are backing that regime, including Russia, need to use their influence to stop Assad from bombarding his people in such a horrific way”.
Russia is opposing a UN bid to order a full investigation of the suspected chemical attack in Syria.
12
Though he is currently propping up Syrian President Bashar al-AssadCredit: EPA
12
Mr Trump yesterday met Chinese President Xi Jinping at the tycoon’s Mar-a-Lago resort in FloridaCredit: Getty Images
12
They were expected to talk trade and North KoreaCredit: Getty Images
The US, Britain and France want to send in the Organisation for the Prohibition of Chemical Weapons.
Their UN resolution calls on the Syrian regime to provide flight plans, flight logs and the names of commanders of helicopter squadrons on the day.
Russia has used its veto power to block UN action in Syria seven times so far.
Mr Trump met Chinese President Xi Jinping at the tycoon’s Mar-a-Lago resort in Florida where they were expected to talk about trade and North Korea.
The pair were dining when the Tomahawk attack was launched from the eastern Mediterranean.
For more on this story
12
Listen to Julia Hartley-Brewer from 10am on talkRADIO
12