A drone strike in northwestern Syria on Sunday killed two senior commanders with an al-Qaida-linked group, sources said.
The strikes employed twice as many weapons used as in the response to a Syrian chemical attack last year.
President Donald Trump blamed Syrian President Bashar al-Assad for a suspected chlorine attack.
Operations in eastern Syria have been scaled back after U.S. fighter jets fired on hundreds of alleged Russian mercenaries.
The most civilian victims were in Afghanistan, with 108 deaths and 75 injured, the Pentagon said.
In a world gripped by a pandemic and global unrest, it can be difficult to remember that the war in Syria is still happening.
Spc. Jesse Spyker, 20, was referred to court-martial on Feb. 21.
Investigators turned up war crimes by Russian forces, Syrian troops, al-Qaida's affiliate, and Turkey-backed Syrian fighters.
The fighters were among at least eight Hezbollah members who died in Turkish attacks.
NATO called on Syria and Russia to halt their airstrikes following the killing of 33 Turkish soldiers in northeastern Syria.