The Russian military on Friday said it had proof that an alleged chemical weapons attack in Syria's Eastern Ghouta was staged on orders from London.
Davis, who in 2013 voted against taking military action against Syrian President Bashar al-Assad's government, said that his decision then was based on a lack of clear evidence and a lack of a clear plan.
French President Emmanuel Macron claimed that France had "proof" the Assad regime used chemical weapons in Douma at the weekend, and would support any United States action.
May spoke with US President Trump Thursday night about the worldwide response to Syria, and they "agreed that the Assad regime had established a pattern of risky behavior in relation to the use of chemical weapons", according to a Downing Street statement.
Ministers said there was need to "deter the further use of chemical weapons by the Assad regime", and alleviate the humanitarian situation, a Downing Street statement said. On Wednesday, Trump appeared to suggest airstrikes were imminent, warning Russia, Syria's key ally, to "get ready" for military action.
She said nearly a century of global aversion to the use of chemical weapons had been eroded in Douma and Salisbury.More news: BJP ministers' resignations being sent to J&K CM: Ram Madhav
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"We can not allow the use of chemical weapons to become normalized - either within Syria, on the streets of the United Kingdom or elsewhere", May told reporters in Downing Street.
May said she would address parliament on Monday about the strikes.
It said they all agreed with her on "the importance of restoring the worldwide norm that the use of chemical weapons is never acceptable".
The leader of Britain's opposition Labour Party Jeremy Corbyn said on Saturday there was no legal basis for British strikes against Syria and such action would encourage others to behave in the same way.
"Britain should be playing a leadership role to bring about a ceasefire in the conflict, not taking instructions from Washington and putting British military personnel in harm's way", Corbyn said.