Video: Trump orders strikes against Syria
The Pentagon said one of the targets was a scientific research center located in the greater Damascus area.
The second target was a chemical weapons storage facility west of the city of Homs.
The third target, which was also near Homs, contained both a chemical weapons equipment storage facility and a command post.
British Prime Minister Theresa May said she had authorized British armed forces "to conduct co-ordinated and targeted strikes to degrade the Syrian regime's chemical weapons capability".
The military action is not about intervening in Syria's civil war or changing its government, she said.
The French army joined the US and Britain in an operation targeting the clandestine chemical arsenal in Syria, French President Emmanuel Macron announced in an official statement early Saturday.
"I ordered the French armed forces to intervene tonight, as part of an international operation conducted in coalition with the United States of America and the United Kingdom and directed against the clandestine chemical arsenal of the Syrian regime," Macron said.