A 42-year-old Navy sailor whose many decorations included the Bronze Star has been identified as the first member of the American armed forces to be killed in combat in Syria, the Defense Department said on Friday.

The sailor, Senior Chief Petty Officer Scott C. Dayton, lived in Woodbridge, Va., and was assigned to a bomb-disposal unit based in Virginia Beach, the Pentagon said in a news release.

He was killed by an improvised bomb on Thursday in northern Syria, where the Americans have been helping to organize an offensive against the Islamic State.

American warplanes have been bombing targets inside Syria to help tens of thousands of militia fighters try to oust the Islamic State from Raqqa, the extremist group’s stronghold in the country.