U.S., British and French forces launched air strikes on Syria in response to a suspected poison gas attack that killed dozens of people, aiming to degrade its chemical weapons capabilities in the biggest intervention yet in the conflict by Western powers.

U.S. President Donald Trump announced the military action from the White House, saying the three allies had “marshalled their righteous power against barbarism and brutality.”

With more than 100 missiles fired from ships and manned aircraft, the allies struck three of Syria’s main chemical weapons facilities, U.S. Defense Secretary Jim Mattis and Joint Chiefs of Staff Chairman General Joseph Dunford said.

According to Reuters, the targets included a Syrian center in the greater Damascus area for the research, development, production and testing of chemical and biological weaponry as well as a chemical weapons storage facility near the city of Homs. A third target, also near Homs, contained both a chemical weapons equipment storage facility and a command post.

“We are prepared to sustain this response until the Syrian regime stops its use of prohibited chemical agents,” the U.S. president said in a televised address.