Many opposition MPs have questioned May's decision to join the attack without seeking parliamentary approval.
"The UK prime minister is accountable to parliament, not to the whims of a USA president", he wrote in a weekend letter to May and reiterated in the House of Commons on Monday.
May faced down her domestic critics as France's premier defended the "proportionate" response to the use of chemical weapons.
British Royal Air Force jets joined American and French warplanes and ships in hitting targets in Syria early on Saturday in response to a reported chemical attack by the Syrian Government in the town of Douma.
"Let me be absolutely clear: we have acted because it is in our national interest to do so", she will add.
The alleged use of chemical weapons in Syria can not be a justification for military airstrikes in a territory of a sovereign state without the authorisation of the UNSC. She is now enjoying global support for her action in Syria and against Moscow over a nerve agent attack on a former Russian spy in Britain.
But Mrs May said this would effectively give Russian Federation a "veto on our foreign policy" as the country has blocked previous resolutions on Syria.
"The Syrian regime has reportedly been attempting to hide the evidence by searching evacuees from Douma to ensure samples are not being smuggled from this area", she said. "And a wider operation to hide the facts of the attack is underway, supported by the Russians", she said. SO24 votes are typically on bland motions acknowledging the existence of the debate, although opposition parties have previously submitted stronger-worded motions.
But she will be grilled over why she broke with a convention to seek Parliamentary approval for the action, a decision that she and her ministers say was driven by the need to act quickly.
"We have not done this because President Trump asked us to, we have done it because we believed it was the right thing to do, and we are not alone", May said to cheers.
Britain's ambassador to the Netherlands and permanent representative to the chemical weapons watchdog OPCW, Peter Wilson, centre, talks to embassy employees after a press conference in The Hague.
Some French opposition leaders have criticized the strikes, saying they were not legitimate.
Mr Johnson, speaking at a summit of European Union foreign ministers, stressed it was "not an attempt to change the tide of the war in Syria or to have regime change" and "the Syrian war in many ways will go on in its awful, miserable way". Some people will suspect that that didn't happen because of governmental concerns that they couldn't get the vote in Parliament.
The ministers said the European Union "understands" the need for the coordinated U.S, French and British airstrikes following the suspected April 7 chemical attack.
Britain has said there are no plans for future strikes against Syria, but foreign minister Boris Johnson warned President Bashar al-Assad that all options would be considered if chemical weapons were used against Syrians again.
"There is the need to give a push to the United Nations -led process", Mogherini said.
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