The British Prime Minister Theresa May fully advocated her country's action to join the United States and French forces in a strike on Syrian capital Damascus on Friday, terming the operation right and legal.
"It is not about regime change", May said in a statement.
May said "a significant body of information including intelligence" pointed to Syrian government responsibility for a suspected chemical attack last Saturday.
"This collective action sends a clear message that the worldwide community will not stand by and tolerate the 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".
"I think it is right that the global community has come together and said we will not accept this", she added.
Speaking in Downing Street, May said the military strikes should be a "warning to Russia" before holding the Syrian government accountable for the chemical attack.
Theresa May declined to say whether Syrian President Bashar al-Assad should stay in power and said talks with allies would continue on finding a political solution to the civil war.More news: Thousands say emotional goodbye to 'Mama Winnie' at funeral service
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"While the full assessment of the strike is ongoing, we are confident of its success", she added.
Britain's ambassador to the United Nations says Russia's claims are 'grotesque, freaky and a blatant lie'.
Britain's defense ministry said "very careful scientific analysis" had been applied to maximize the destruction of stockpiled chemicals while minimizing any risk of contamination to surrounding areas.
Correspondents from the British and world press also asked the prime minister to explain what role can the Parliament play in making a decision to attack another sovereign country.
The UK has begun air strikes against Syrian chemical weapons sites.
Parliament is not due to reconvene until Monday, following its Easter recess.
Besides Trump, French President Emanual Macron said in a statement that they also could not tolerate the normalisation of the use of chemical weapons.
Polls in recent days have shown public wariness of military intervention in Syria, with Britain still haunted by its participation in the US-led invasion of Iraq.
Scottish First Minister Nicola Sturgeon also said the strikes risked "dangerous escalation".