President Trump ordered airstrikes on Saturday against the Islamic State in northern Somalia, the first major U.S. military operation overseas since he took office.

Defense Secretary Pete Hegseth said in a statement that the military’s initial assessment was that “multiple operatives” in the remote Golis Mountains in the country’s north were killed in the strikes, and that no civilians were harmed.

The strikes were conducted by Navy and Air Force warplanes, including F/A-18 fighter jets from the aircraft carrier Harry S. Truman operating in the Red Sea, three Defense Department officials said.

“This action further degrades ISIS’s ability to plot and conduct terrorist attacks threatening U.S. citizens, our partners and innocent civilians,” Mr. Hegseth said.

The strikes were more symbolic than substantive, several U.S. military and defense officials said, meant more to burnish Mr. Trump’s image as a commander in chief protecting the country from terrorists in the early days of his administration than to neutralize a serious threat.

On Thursday, the military’s Central Command said a U.S. airstrike in northwest Syria had killed a senior operative in Hurras al-Din, an Al Qaeda affiliate.