Defense Agency chief Shigeru Ishiba suggested Sunday that Japan should consider revising the Japan-U.S. Status of Forces Agreement if bilateral discussions to prevent "arbitrary use" of the accord do not produce a solution in the handling of the recent helicopter crash in Okinawa.

"If SOFA can be used arbitrarily, we have to first discuss how to ensure that this does not occur," Ishiba said on a morning NHK TV program.

But if such a discussion does not provide any practical solution, it may be necessary to start discussing revising the accord, Ishiba said.