Responding to the attacks, British PM Theresa May said that Britain had no other alternative except carrying out military action against the Syrian Chemical weapons facilities operated under Syria's President Bashar al Assad regime.
She said: "In Douma, last Saturday a chemical weapons attack killed up to 75 people, including young children, in circumstances of pure horror".
In the televised address, Mr Trump said the allies would continue their response until Bashar Al-Assad, the Syrian president, ceased its use of chemical weapons.
"It is about a limited and targeted strike that does not further escalate tensions in the region and that does everything possible to prevent civilian casualties", she said.
The UK has begun air strikes against Syrian chemical weapons sites.
Theresa May approved deployment of British forces in the missile strike against Syria after government lawyers told her it was lawful on humanitarian grounds.
"We have sought to use every possible diplomatic channel to achieve this", the prime minister said.
May is not obliged to win parliament's approval before ordering military action, but a non-binding constitutional convention to do so has been established since a 2003 vote on joining the USA -led invasion of Iraq.
"This collective action sends a clear message that the global community will not stand by and tolerate the use of chemical weapons", May told a press conference.
But she also drew a link with the nerve agent attack on Russian former spy Sergei Skripal and his daughter Yulia in Salisbury.
Russia, which intervened in the war in 2015 to back Assad, has denied there was a chemical attack and has accused Britain of helping to stage the Douma incident to stoke anti-Russian hysteria. This massacre was a significant escalation in a pattern of chemical weapons use by that very awful regime.
"It was right to take the action that we have done in the timing that we have done", she said.
"I have done so because I judge this action to be in Britain's national interest", she added.
The Ministry of Defence (MoD) said that four RAF Tornado jets were deployed to launch missiles at a Syrian military facility.
Williamson told BBC radio that all British crews returned safely and early indications were that the strikes had been "highly successful".
A YouGov poll for The Times newspaper this week indicated that only a fifth of voters believed that Britain should launch attacks on Syrian military targets and more than two-fifths opposed action. These are not the actions of a man, they are crimes of a monster instead.
"Bombs won't save lives or bring about peace", Jeremy Corbyn, leader of the main opposition Labour Party, said in a statement.
Vince Cable, leader of the Liberal Democrats, said: "Riding the coattails of an erratic USA president is no substitute for a mandate from the House of Commons".