At a press conference in Downing Street, Mrs May said: 'There is no graver decision for a prime minister than to commit our forces to combat and this is the first time I have had to do so.
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. A spirited debate is expected.
US, UK and France launch air strikes in response to Saturday's suspected chemical attack that killed dozens in the Syrian town of Douma, as Russian Federation and Iran warn of consequences. 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".
"Never said when an attack on Syria would take place".
However, initial responses from some Labour and SNP MPs criticised May for not seeking parliamentary approval for the strikes - something which Labour leader Jeremy Corbyn had called on her to do.
After meeting for more than two hours, the Cabinet backed May's plan to work with the US and France "to coordinate an worldwide response".
"The combined American, British, and French response to these atrocities will integrate all instruments of our national power - military, economic, and diplomatic".
Barrel bombs are large containers that are packed with fuel, explosives and scraps of metal. So there is no practicable alternative to the use of force to degrade and deter the use of chemical weapons by the Syrian Regime.
The assessment cites "the absence to date of chemical samples analyzed by our own laboratories".
He said Moscow has "irrefutable information that it was another fabrication".
It concludes that there is "no plausible scenario other than that of an attack by Syrian armed forces".
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"Significant bodies of influence have said that the Syrian regime is responsible".
"The situation in Syria is horrific, the use of chemical weapons is something the world has to prevent", he said.
The Russian military says Syria's Soviet-made air defence systems have downed 71 out of 103 cruise missiles launched by the United States and its allies.
Labour Party leader Jeremy Corbyn was quoted by the Guardian that "Parliament should always be given a say on military action" and warned against the threat that air strikes could escalate into a "hot war" between the US and Russian Federation.
"Any possible action will only cause more instability in the region and threaten global security and peace", Syrian state TV quoted Assad as saying at a meeting Thursday with a high-level Iranian delegation in Damascus.
Following the announcement, the U.S. said strikes had been launched at 9pm EST (2am BST) and had destroyed important infrastructure at three sites connected with the Syrian regime's chemical weapons programme.
He notes that Russian Federation in the past refrained from providing Syria with its state-of-the-art S-300 air defence missile systems on Western prodding but could reconsider it now.
"That is what our country has always done and that is what we will continue to do".
She said that the objective of the strike was to "degrade and deter" the Syrian regime in its use of chemical weapons.
Syrians crowded onto the streets in noisy demonstrations of defiance afterward and their ally Russian Federation denounced the attack.
In an address, Trump said the attack had been undertaken "to establish a strong deterrent against the production, spread and use of chemical weapons". Earlier, Syria's ambassador to the United Nations, Bashar Jaafari, told reporters in NY that those investigators were to arrive Thursday and Friday.
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Trump has said he didn't know about payments Daniels, which, according to media reports, is cooperating with Federal investigators.