French President Emmanuel Macron said on Saturday that he had ordered a military intervention in Syria alongside the United States and Britain in an attack on the chemical weapons arsenal of the country's regime.
US President Donald Trump said earlier that he had ordered precision strikes targeting Syrian President Bashar al-Assad's chemical weapons capabilities after a poison gas attack that killed at least 60 people last week.
Macron said the attack had been limited so far to Syria's chemical weapons facilities.
The French presidency issued a video on Twitter showing what it said were Rafale war planes taking off as part of the intervention.
"We cannot tolerate the recurring use of chemical weapons, which is an immediate danger for the Syrian people and our collective security," a statement from the Elysee presidential office said.
"On April 7, dozens of men, women and children were massacred in Douma, with the use of a chemical weapon in a total violation of international rules (...) The red line established by France in May 2017 was crossed," Macron said.
He added that the facts and the responsibility of the Syrian regime were beyond doubt.
British Prime Minister Theresa May also said she had authorised British forces to conduct strikes against Syria.
Macron, who tweeted a picture of himself in a meeting room with military and diplomatic advisers, said a debate about France's military involvement would take place in parliament.
The French air force has been active in Syria since 2015 to fight Islamic State group but it was the first time it carried out an attack against the Syrian regime.