A US military Black Hawk helicopter crashed off the southern coast of Yemen while training its crew, leaving one service member missing, local media reported.
It is still unknown what caused the incident but the USA military said it will investigate the crash incident.
Officials have not yet identified those onboard the aircraft at the time of the crash or the unit the aircraft belonged to.
The Yemen branch of al Qaeda is the most active terror network, operating in the country torn by bloody conflict between government forces and Houthi rebels, who took over the capital, Sanaa, in 2015.
Last month, a military transport plane crash killing 16 service members including elite special operations forces in northern Mississippi.
A small team of U.S.
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Yemen, located on the southern end of the Arabian Peninsula, is engulfed in the years-long civil war.
Several thousand USA sailors and Marines also routinely operate in the region as part of a naval amphibious ready group.
A small number of US troops were on the ground in Yemen earlier this month to provide "intelligence sharing" with government forces battling al-Qaida loyalists there, the Washington Post reported.
The cause of the Black Hawk helicopter's crash is unknown.
The U.S. Coast Guard recently said that it had suspended its search off Hawaii for five Army aviators missing since their Black Hawk helicopter crashed earlier this month.
Also this month, a Marine Corps MV-22 Osprey crashed off the coast of Australia.