A US military aircraft crashed into waters south of the Muroto Cape on Shikoku island (Library picture: US Department of Defense).
The US Marines says five crew members missing after a crash involving military aircraft have been declared dead.
An F/A-18 fighter jet and a KC-130 refuelling aircraft collided and crashed off Japan's south-western coast last week.
Two crew members were rescued, with one confirmed by the US Marine Corps to have died later.
There were two crew members in the F/A-18 and five in the KC-130, when they crashed into the sea south of the Muroto Cape on Shikoku island.
The incident took place 200 miles off the coast, according to the US military.
Japanese officials said it occurred closer to the coast, about 60 miles, and that is where the search and rescue mission found two crew members.
Last month, a US Navy F/A-18 Hornet from the aircraft carrier USS Ronald Reagan crashed into the sea southwest of Japan's southern island of Okinawa, with its two pilots being rescued safely.
In mid-October, an MH-60 Seahawk also belonging to the Ronald Reagan crashed off the Philippine Sea shortly after takeoff, causing non-fatal injuries to a dozen sailors.
More than 50,000 US troops are based in Japan under the bilateral security pact.