An aircraft carrying 11 crew and passengers crashed into the Pacific Ocean Wednesday while on the way to the aircraft carrier USS Ronald Reagan, the Navy said.
Japanese Minister of Defense Itsunori Onodera told reporters the U.S. Navy had informed him that the crash in the Philippine Sea may have been a result of engine trouble. "Personnel recovery is underway and their condition will be evaluated", the Navy had stated.
NHK says the aircraft was a C2 transport plane. The number of fatalities, injuries and cause of the crash was not immediately clear as rescue crews rushed to the plane.
The USS John S. McCain collided with a tanker off Singapore in August, killing 10 sailors and injuring five others.
Seven U.S. sailors were killed when the USS Fitzgerald collided with a Philippine-flagged container ship in the middle of the night off the coast of Yokosuuka on June 17.
There were also two more, lesser-known incidents.
Ten or eleven crew members were onboard the aircraft before it crashed around 2:45 p.m. local time (0545 GMT), said local reports.
The drills come as tensions persist between Washington and North Korea over its missile and nuclear programme.