French President Emmanuel Macron says his nation, the United States and Britain have launched a military operation against the Syrian government’s “clandestine chemical arsenal.”

Macron says in a statement Saturday that France’s “red line has been crossed” after a suspected chemical attack last week in the Syrian town of Douma.

He says there is “no doubt” that the Syrian government is responsible. President Bashar Assad’s government denies responsibility.

Macron says the operation is limited to Syria’s abilities to produce chemical weapons. He is not giving details about what equipment is involved in the operation or what sites it is targeting.