The government is considering legal revisions to allow for "preparatory" action by Maritime Self-Defense Force vessels that would enable them to deal quickly with suspicious ships spotted off Japan, Defense Agency chief Gen Nakatani said Friday.

"It is necessary to prepare for defensive action on the seas," Nakatani said, referring to the Self-Defense Forces Law. "If a law is necessary for such preparatory action, then we have to consider revising the law."

His remarks follow criticism of the government's response to a suspected North Korean spy ship that sank in ember in the East China Sea after exchanging fire with the Japan Coast Guard, which encountered the vessel in Japanese waters and gave chase. MSDF craft failed to arrive at the scene in time.