The United States has warned it "is locked and loaded" to strike Syria if there are any more chemical attacks, hours after more than 100 bombs targeted facilities in Damascus and Homs said to be associated with the use of chemical weapons.
Speaking to an emergency session of the UN Security Council on Saturday, Nikki Haley, the US ambassador to the United Nations, said: "If the Syrian regime uses this poisonous gas again, the United States is locked and loaded.
"When our president draws a red line, our president enforces the red line."
The US, UK and France targeted three sites across Syria on Saturday, including: The Syrian Scientific Studies and Research Centre in Damascus' Barzeh district, the Him Shinshar Chemical Weapons Storage Facility, 20km west of Homs and the Him Shinshar Chemical Weapons Bunker Facility, just more than 7km from the storage facility.
Haley said the US and its allies "acted, not as revenge" but to "deter the future use of chemical weapons by holding the Syrian regime responsible for its atrocities against humanity".
However, her Russian counterpart, Vassily Nebenzia, called on the Security Council to condemn the attacks.
"Today is not the day to shirk your responsibilities," he said. "The whole world is looking at you. Take a principled stand."
But Russia failed to garner the necessary votes, and was instead handed a stinging diplomatic defeat.
Only three countries - Russia, China and Bolivia - backed the resolution which called the US and its allies' strikes an "aggression" against Syria.
Eight countries voting against, and four countries abstained - Ethiopia, Kazakhstan, Peru and Equatorial Guinea.
"Today is a very sad day for the world, the UN, its charter, which was blatantly, blatantly violated," Nebenzia said.
Bashar Jaafari, Syria's ambassador to United Nations, said the strikes were an "attack against international law," and called on the three countries to stop supporting "terrorists" in Syria.
He said members of the international chemical weapons watchdog, the Organization for the Prohibition of Chemical Weapons, arrived on Saturday in Damascus and were to meet Syrian authorities.
"My government will, of course, provide every support to this delegation for it to carry out its mission successfully," Jaafari said.
The attacks on Saturday came in response to a suspected chemical weapons attack in the former rebel stronghold of Douma last weekend.
Around 70 civilians suffocated to death as they tried to seek shelter from government air raids and barrel bombs.
US President Donald Trump took to Twitter and thanked France and the UK for "their wisdom and the power of their fine military" in an early morning Tweet.
"A perfectly executed strike last night. Thank you to France and the United Kingdom for their wisdom and the power of their fine Military. Could not have had a better result. Mission Accomplished!"
A Pentagon briefing later said the attacks had "set the Syrian chemical weapons program back for years".
Meanwhile, Russian President Vladimir Putin, described the strikes as an "act of aggression" and warned they could worsen the humanitarian crisis in Syria.
Only 10 days ago, Trump told national security aides that he wanted US forces out of Syria in about six months.
The US president was adamant that it was time to bring them home after largely defeating the Islamic State of Iraq and the Levant (ISIL, also known as ISIS) group.
"Very soon, very soon, we're coming out," Trump said to a crowd in Richfield, Ohio, on March 30.
"We're going to get back to our country, where we belong, where we want to be," he said.
But with Saturday's attacks, Trump has abruptly deepened US involvement in Syria.
Aides told Reuters news agency that Trump's attitude changed when he was shown images of Syrians allegedly killed by the chemical weapons last Saturday.
The attacks come about a year after he first ordered air raids against Syrian targets to retaliate for an earlier use of the banned substances.