The UK has begun air strikes against Syrian chemical weapons sites.
Prime Minister Theresa May said there was “no practicable alternative to the use of force” to deter the use of chemical weapons by the Syrian regime.
She added that the strikes were not about “regime change”.
The strikes, in collaboration with the US and France, are in response to an alleged chemical attack on the Syrian town of Douma last week.
Several large explosions have been heard in the Syrian capital Damascus.
In a statement Mrs May said that the Syrian regime had demonstrated a “persistent pattern of behaviour” when it came to the use of chemical weapons, that “must be stopped”.
“We have sought to use every possible diplomatic channel to achieve this,” the prime minister said.
“This is not about intervening in a civil war. It is not about regime change.
“It is about a limited and targeted strike that does not further escalate tensions in the region and that does everything possible to prevent civilian casualties.”