“Operations (of the helicopters) aimed at search and rescue are necessary for the United States to meet its obligations under the Japan-U.S. Security Treaty,” said Defense Minister Itsunori Onodera at a news conference on Aug. 15.

Onodera also emphasized the helicopters’ contribution to the rescue operations in the March 2011 Great East Japan Earthquake and tsunami.

“As they played an important role in (the U.S. military's) Operation Tomodachi emergency rescue activities at the time of the Great East Japan Earthquake, they can contribute to our country’s disaster-relief efforts as well,” said Onodera.

An HH-60 helicopter based at the Kadena Air Base in Okinawa Prefecture crashed on the premises of the U.S. Marines Corps’ Camp Hansen during a training mission on Aug. 5, killing one crew member.

U.S. forces grounded the helicopters the day following the accident, but announced on Aug. 14 they would resume flights of the rescue helicopters, without determining the cause of the fatal crash.

On Aug. 6, Onodera made a request to U.S. Ambassador to Japan John V. Roos that the U.S. military refrain from operating the helicopters until it determines the cause of the accident and develops preventive measures.

However, he also said U.S. forces’ planned safety measures are enough for Japan to accept the resumption of operations.

“I requested they determine the cause of the accident and prevent a recurrence,” Onodera said. “The U.S. military has credibly explained its safety measures.”

But U.S. forces still have not provided an explanation on the cause of the crash.

“There was no explanation,” said Onodera. “Something concrete will be revealed as the United States is compiling a report.”