The U.S. military says a Black Hawk helicopter crashed off the coast of Yemen during a training mission.
U.S. Central Command said in a statement that five service members aboard the aircraft had been rescued after the crash on August 25, which took place about 30 kilometers off the southern coast of Yemen.
It said a search was under way for one U.S. service member.
The U.S. military did not say what was the cause of the crash.
The United States has been carrying out air strikes against Al-Qaeda in Yemen.
U.S. Special Operations forces have also conducted ground raids, including one in January in which a U.S. Navy Seal was killed.
Based on reporting by Reuters and AP