She added that the strikes were not about "regime change".
Four British fighter jets struck a military base near Homs where Britain said Syrian government forces were holding chemical weapon components.
May said intelligence and open source accounts indicated that the regime was behind the attack in Douma last Saturday. "Yet... the global community is not convinced that a chemical attack took place in Douma, and wants to see the results of the ongoing OPCW investigation... to say that "there is no practicable alternative to the use of force if lives are to be saved" is hypocritical, to say the least", the statement says.
Yesterday Prime Minister Theresa May insisted the military action was "legal" and defended the decision to go ahead without securing the backing of Parliament.
"This collective action sends a clear message that the global community will not stand by and tolerate the use of chemical weapons", May said at a press conference, calling the military action "right and legal".
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.
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.
"I have done so because I judge this action to be in Britain's national interest", she added.
Over 100 missiles were fired on the morning of Saturday, April 14, targeting what representatives of coalition forces called chemical weapons sites in retaliation for an earlier poison gas attack.
"We are reassured that the military action is strictly targeted and limited in its objective".
Shortly after the military strikes were launched, Scotland's first minister Nicola Sturgeon said United Kingdom foreign policy should be set by Parliament and not Donald Trump after the U.S., United Kingdom and France bombed targets in Syria.
Former Prime Minister David Cameron lost a parliamentary vote on air strikes against Assad's forces in 2013 when 30 Conservative lawmakers voted against action, with many Britons wary of entering another conflict after intervention in Iraq, Afghanistan and Libya failed to bring stability to the region. "The opposition does not operate helicopters or use barrel bombs".