The strikes also did not target the Bashar al-Assad regime's use of, or access to conventional weapons.
At a Pentagon briefing, director of the Joint Chiefs Lieutenant General Kenneth F McKenzie said the strikes were precise, overwhelming and effective, but that some of Syria's chemical weapons infrastructure remained.
"I think we've dealt them a severe blow," he said.
"But I would say there's still a residual element of the Syrian program that's out there.
At an emergency meeting of the UN Security Council, the United States ambassador Nikki Haley warned that further strikes would come if chemical attacks continued.
The US appeared to have drawn that line this time last year, when it launched 59 Tomahawk missiles into Syria in response to a similar attack.