A Navy Seal died of injuries suffered during a weekend raid against al-Qaida militants in Yemen, the United States military said in a statement.
Three other Navy Seals were wounded in the operation on Saturday against members of al-Qaida in the Arabian Peninsula.
The militant organization has remained a potent threat amid an extended civil war in Yemen.
The incident marks the first time a member of the U.S. military has died in combat since President Donald Trump took office a little more than a week ago.
The ground operation, which had been planned for months, was authorized by Trump, according to U.S. officials familiar with the mission.
Trump has pledged to wage a more aggressive campaign against militant groups worldwide.
In a statement released by the White House, Trump called the raid “successful” and that it resulted in the capture of intelligence that would “assist the U.S. in preventing terrorism against its citizens and people around the world.”
“Americans are saddened this morning with news that a life of a heroic service member has been taken in our fight against the evil of radical Islamic terrorism,” Trump said in the statement.