The three nations opted to strike Syria for its apparent use of chemical weapons without waiting for a report from the inspectors because they were convinced that the Assad government had used chlorine and sarin nerve gas in Douma.
British Foreign Secretary Boris Johnson reinforced this point on April 16 as he arrived at a meeting of European Union foreign ministers in Luxembourg.
On Saturday, he checked out the smoldering rubble of a suspected chemical weapons facility in Damascus.
That agreement was brokered by Moscow to avert retaliatory United States strikes in the wake of a sarin attack in the rebel-held Eastern Ghouta suburbs of Damascus on August 21, 2013 that reportedly killed more than 1,400 civilians.
Mrs May is due to give a Commons statement on Monday before facing questions from MPs.
Mrs May will ask for an emergency debate to allow more time for discussion in a nod to the fury among MPs at not being consulted, but she is not offering a vote.
Theresa May's decision to authorise action without MPs' backing has been criticised by Labour leader Jeremy Corbyn, who said she could "easily" have recalled Parliament or delayed her decision until MPs returned to Westminster from the Easter recess.
"Where is the legal basis for this?" he said.
Syria's civil war has killed more than 350,000 people since it started in 2011 with the brutal repression of anti-government protests.
Mr Corbyn said that if Britain wants to "get the moral high ground around the world" it must abide by worldwide law for taking military action.
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Ibrahim al-Marashi, an associate professor of history at California State Univesity, said that the USA strikes embody "largely symbolic actions with little effect on the ground".
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"That surely would save a lot of lives". And he doubts that sanctions against Russian Federation will move the needle.
"Contacts with the Russians have not been good", Johnson admitted on the Andrew Marr Show.
The West has accused Syria of failing to live up to its commitment to scrap its chemical weapons programme under a deal reached between the United States and Russian Federation.
Mara Karlin, a former senior Pentagon official, said: "Let's not kid ourselves, Mr Assad has no shortage of tools in his destructive and deadly arsenal".
United States leader Trump exclaimed "Mission Accomplished" after the pre-dawn strikes that lit up the sky around Damascus in a tweet that drew swift derision from his critics and parallels with president George W. Bush's notoriously premature Iraq war victory speech on an aircraft carrier 15 years ago.
The MoD added the facility was located "some distance" from "concentrations of civilian habitation", and the risk of contamination to the surrounding area had been minimised.
Russian President Vladimir Putin said the military strikes violated the U.N. Charter and that if they continue, "it will inevitably entail chaos in global relations", according to a Kremlin statement on Sunday.
A Western draft resolution obtained by AFP at a meeting of the UN Security Council Saturday calls for unimpeded deliveries of humanitarian aid and enforcement of a ceasefire, along with demands that Syria engage in UN-led peace talks.