U.S. officials said 14 militants were killed, along with one U.S. service member, in a commando raid on an Al-Qaeda stronghold in Yemen.
The American death in the January 28 raid is the first known U.S. combat death since President Donald Trump took office last week.
Few details about the incident were released.
An unnamed military official told Reuters that the U.S. special forces raid was authorized by Trump and was aimed at gathering intelligence about Al Qaeda in the Arabian Peninsula.
The official said American forces did not seize any militants or take any prisoners off-site.
The Pentagon said 14 Al-Qaeda members were killed.
Earlier reports quoted unidentified Yemeni security officials as saying several helicopters took part in the operation in Bayda Province.
AFP reported a provincial official as saying as many as 41 militants and 16 civilians were killed.
A civil war began in Yemen in 2011 that pits Shi'ite Huthi rebels against Al-Qaeda fighters and the Saudi-backed Yemeni government of Abd-Rabbu Mansur Hadi, which was forced out of the capital in 2015 to the southern city of Aden.
Saudi Arabia leads a 10-country coalition fighting the Huthi rebels and Al-Qaeda militants.
The United States announced that it would assist with intelligence and logistics with Saudi Arabia and Egypt. It has previously carried out several drone strikes in the country.