Downing Street said an 'international response' would be coordinated with the United States and France
Cabinet has agreed to "take action" in order to deter the use of chemical weapons in Syria.
A military strike is expected against Bashar al-Assad's regime.
Downing Street said an "international response" would be coordinated with France and the US.
Theresa May's top circle agreed the Syrian dictator was "highly likely" behind the suspected chemical weapons attack in Douma on the weekend and has a track record of doing so.
The Prime Minister called the urgent meeting which lasted for two hours. In it every member of May’s team is said to have spoken. She said the Douma incident was a "shocking and barbaric act" which killed dozens of innocent people.
May said the attack was "a further example of the erosion of international law in relation to the use of chemical weapons."
A Downing Street statement said: "Following a discussion in which every member present made a contribution, cabinet agreed it was vital that the use of chemical weapons did not go unchallenged.
"Cabinet agreed on the need to take action to alleviate humanitarian distress and to deter the further use of chemical weapons by the Assad regime.
"Cabinet agreed the prime minister should continue to work with allies in the United States and France to coordinate an international response."
Jeremy Corbyn, as well as Conservative backbenchers, has demanded any military action require parliamentary approval.
But it is possible that an attack could come as early as Thursday night. British attack submarines are said to be on standby in the Mediterranean Sea, while RAF fighter jets based in Cyprus could also be used.
President Trump has also tweeted "Get ready Russia, because they [missiles] will be coming, nice and new and 'smart!'"
Russian state television
has instructed viewers to stockpile supplies and prepare for war.
