NATO Secretary-General Jens Stoltenberg addresses a news conference after a meeting of the Alliance's 29 ambassadors in Brussels, Belgium April 14, 2018.
In a "combined operation" on Friday night, the UK, US and France launched airstrikes in response to a suspected chemical weapons attack that left up to 75 dead in Douma last week.
Iran's Supreme Leader Ayatollah Ali Khamenei said the attack was a "crime" and declared Theresa May, Donald trump and Emmanuel Macron "criminals".
A US -led airstrike campaign against Syria was in response to a suspected chemical attack against civilians last weekend.
The Prime Minister said: "We can not allow the use of chemical weapons to become normalised within Syria, on the streets of the United Kingdom, or anywhere else in our world".
After a debriefing of North Atlantic Treaty Organisation ambassadors by the three allies on Saturday, Mr Stoltenberg said that "before the attack took place last night, North Atlantic Treaty Organisation allies exhausted all other possible ways to address this issue to the UNSC by diplomatic and political means".
He added, "But since this was blocked by Russian Federation, there was no other alternative".
Russia's Foreign Ministry says the attack was an attempt to derail an investigation into a purported chemical attack.
Ahead of an impartial investigation by the Organization for the Prohibition of Chemical Weapons, the United States, Britain and France joined the chorus, accusing the Bashar al-Assad government of using chemical weapons.
Jeremy Corbyn said the military action against Syria was "legally questionable" and makes real accountability for war crimes less likely.
Jeremy Corbyn has criticised the Prime Minister for not seeking parliamentary approval, adding that "bombs won't save lives or bring about peace".
Pence says he's hopeful that Russian Federation and Iran will "once and for all abandon chemical weapons" against innocent civilians.