British Prime Minister Theresa May summoned her senior ministers to a special cabinet meeting on Thursday to discuss joining the United States and France in possible military action against Syria after a suspected poison gas attack on civilians.
She said: "In Douma, last Saturday a chemical weapons attack killed up to 75 people, including young children, in circumstances of pure horror. It is not about regime change", May said in a statement made from her country residence at Chequers just minutes after U.S. President Donald Trump announced the strikes from the White House.
It added that it believed the Syrian government had committed a "war crime and a crime against humanity" with chemical weapons use and that attempts to find a unified worldwide approach through the United Nations had been blocked by Damascus-ally Moscow.
"I have done so because I judge this action to be in Britain's national interest", she added.
But earlier on Friday, Nikki Haley, the U.S. ambassador to the United Nations accused Assad of using chemical weapons over 50 times during the civil war.
Corbyn has written to May seeking assurance that there would be no further bombing raids and urged the government to negotiate a pause in the Syrian civil war.
Mr. Corbyn said that rather than a military action, what was needed was a coordinated global drive for a ceasefire and a negotiated UN-led settlement.
"The combined American, British and French response to these atrocities will integrate all instruments of our national power: military, economic and diplomatic", Trump added.
In an article for the Guardian, the Labour leader said the attack by the west was "either purely symbolic - a demolition of empty buildings, already shown to be entirely ineffective as a deterrent".
Former Labour foreign secretary David Miliband, now head of humanitarian relief group the International Rescue Committee, said military action needed to be part of a wider political strategy.
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On the same day, protesters led by Pashinyan seized the building of Armenia's Public Radio for around an hour. Several protests loosely organised around the slogan "No to Serzh", have been held since March.
Jeremy Corbyn called it "legally questionable" in a letter to May.
Russian Defence Ministry spokesman, Major General Igor Konashenkov, released statements by medics from Douma's hospital who said a group of people toting video cameras entered the hospital, shouting that its patients had been struck with chemical weapons and causing panic.
The UK is "confident" that air strikes carried out by Britain, the United States and France on suspected chemical weapons facilities in Syria have been successful, the PM has said.
May said the strikes would "send a clear signal to anyone else who believes they can use chemical weapons with impunity".
"Most worrying, is that she has acted at the behest of presidential tweets and sidelined parliament", he said.
At the press conference, May outlined the intelligence that led Britain to join the US and France in launching more than 100 missiles against Syrian government targets overnight.
Russia, which intervened in the war in 2015 to back Assad, has denied there was a chemical attack and has accused Britain of helping to stage the Douma incident to stoke anti-Russian hysteria.
But rival politicians and some Conservative colleagues have called for a parliamentary vote before any British involvement.
British MPs voted against taking military action against Damascus in 2013, in what was widely viewed as an assertion of parliamentary sovereignty on the use of force.
The UK, United States and France launched "precision strikes" in Syria overnight.