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.
The Prime minister spoke to Donald Trump by phone within hours of the meeting, with the two leaders agreeing to work closely together on the global response.
She said the missile attacks had been aimed at deterring President Bashar al-Assad's further use of chemical weapons and were not an attempt to topple the Syrian government.
"Cabinet agreed that the Assad regime has a track record of the use of chemical weapons and it is highly likely that the regime is responsible for Saturday's attack", Downing Street said. He said earlier this week that France was ready to attack the "chemical capabilities" of the Assad regime.
She said nearly a century of global aversion to the use of chemical weapons had been eroded in Douma and Salisbury.
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Under the UN Charter, the United Nations has the primary responsibility for maintaining worldwide peace and security.
It said they all agreed with her on "the importance of restoring the worldwide norm that the use of chemical weapons is never acceptable". Speaking Thursday, Merkel said that the "whole spectrum of measures must be considered" when responding to the use of chemical weapons, adding: "Germany will support all activities with the United Nations security council". May is not required by law to consult the House of Commons, but by convention, members of Parliament expect to be consulted.
Pierce also said France, Britain and the United States support the fact-finding mission of the Organization for the Prohibition of Chemical Weapons (OPCW), which is to investigate the Douma attack.
Top U.K. officials agree world powers should respond to a suspected chemical attack on Syrian civilians.
Trump was also expected to speak to the French president, Emmanuel Macron, about what form the action could take, with the White House saying: "No final decision has been made".