U.S. Defense Secretary Jim Mattis and Marine General Joseph Dunford said three main chemical weapons facilities were targeted at 9 p.m. EST (1 a.m. GMT) by missiles from both the sea and aircraft, which triggered Syrian air defenses.
The Pentagon could not confirm how many missiles hit their targets but said no other attacks were planned.
Mattis and Dunford acknowledged the strike was designed to degrade Syria’s chemical weapons capability without killing civilians or the many foreign fighters in Syria’s multi-sided civil war, particularly those from Russia.
“We were very precise and proportionate,” Mattis said. “But at the same time, it was a heavy strike.”
Last year, 59 Tomahawk cruise missiles fired from the guided missile destroyers USS Porter and the USS Ross struck Syria’s Shayrat air base.