Al-Qaida in the Arabian Peninsula, long seen by Washington as among the most risky branches of the global terror network, has exploited the chaos of Yemen's civil war, seizing territory in the south and east.
It was the first combat casualty of the Trump administration and its first operation in the war-damaged Arabian Peninsula nation against a powerful al Qaeda branch that has been a frequent target of USA drone strikes. But officials say the raid was planned, at least in part, under former President Barack Obama. Trump has pledged to wage a more aggressive campaign against militant groups worldwide.
A two-hour gunbattle ensued after American service members landed on the ground, it said.
The operation, which took place in a remote desert area of Yemen's Shabwa governorate, aimed to obtain intelligence information, including computer material, that was believed to be linked to planning for external attacks. One U.S. soldier died and three were injured.
The US special forces killed Abdulraoof Al Thahab, his brother Sultan, who US officials said were Al Qaeda leaders, and all their family members, the Yemeni official said.
U.S. Army General Joseph Votel indicated the raid was carried out by members of SEAL Team 6.
There has been no confirmation from the USA side. The aircraft dropped an unknown amount of munitions in support of the operation.
US drone strikes targeted and killed three other Al Qaeda members in Yemen a week ago, according to USA officials.
The United States conducted dozens of drone strikes in Yemen throughout Barack Obama's presidency to combat al-Qaida in the Arabian Peninsula, regarded as one of the global militant group's most unsafe branches.
Sources in Al Dhubab, a port village that was the first objective of the operation, said that landmines and rebel snipers were still hampering the pro-government forces from clearing the area. Last week, USA drone strikes hit militants in al-Bayda, killing five over the course of three days.
An MV-22 Osprey helicopter reportedly had to be destroyed after being damaged during the early-morning raid.
"My deepest thoughts and humblest prayers are with the family of this fallen service member", he added.