The UK has joined the US and France in carrying out air strikes on Syria without parliamentary or public approval.
The strikes targeted military bases near the capital Damascus and the city of Homs, in response to last week’s alleged chemical attack on the Syrian town of Douma.
Defence Secretary Gavin Williamson said it was a “highly successful mission”.
But Jeremy Corbyn called the strikes “legally questionable” and said Parliament should have been consulted.
Syrian state media called the strikes a “violation of international law”. Damascus denies carrying out a chemical attack and says it was probably carried out by Syrian rebels to provoke Western intervention.
Prime Minister Theresa May said there was “no practicable alternative to the use of force”.
Mr Williamson added the UK, France and America had played an important role in “degrading the ability of the Syrian regime to use chemical weapons”.
The Ministry of Defence said Storm Shadow missiles were launched by four RAF Tornados at a former missile base 15 miles west of Homs, where they believe the Assad government is stockpiling items used to make chemical weapons.
A spokesperson added the facility was “located some distance from any known concentrations of civilian habitation” and scientific analysis was used to “minimise any risks of contamination to the surrounding area”.
In a statement Mrs May said that the Syrian government had demonstrated a “persistent pattern of behaviour” when it came to the use of chemical weapons, that “must be stopped”.
But she said the operation was not about regime change or escalating the war in Syria.
Meanwhile, the official Sana news agency cited an unnamed source as saying: “When terrorists failed, the USA, France and Britain intervened and committed aggression against Syria.
“The American, French and British aggression against Syria will fail.”
At home Jeremy Corbyn condemned the government’s involvement in the air strikes, saying it “makes real accountability for war crimes and use of chemical weapons less, not more likely”.
He said: “Bombs won’t save lives or bring about peace. This legally questionable action risks escalating further, as US defence secretary James Mattis has admitted, an already devastating conflict and therefore makes real accountability for war crimes and use of chemical weapons less, not more likely.
“Britain should be playing a leadership role to bring about a ceasefire in the conflict, not taking instructions from Washington and putting British military personnel in harm’s way.
“Theresa May should have sought parliamentary approval, not trailed after Donald Trump. The Government should do whatever possible to push Russia and the United States to agree to an independent UN-led investigation of last weekend’s horrific chemical weapons attack so that those responsible can be held to account.”
In a recent YouGov opinion poll only 22 per cent of the British public said they would bank military strikes on Syria.