The government is considering a fresh deployment to Okinawa's main island of a surface-to-ship missile unit as part of a bid to beef up defenses in response to Chinese maritime assertiveness, sources said Tuesday.

Tokyo has been proceeding with a plan to install a surface-to-ship missile unit on Okinawa Prefecture's Miyako Island to bolster its defenses against threats to remote islands in the southwest. But it believes the main island should also have a unit as Chinese naval ships have frequently passed between the two islands — an area known as the Miyako Strait — in the East China Sea.

Miyako Island is located about 290 km southwest of the main island of Okinawa. The armaments to be deployed on the islands are expected to be the Ground Self-Defense Force's Type-12 surface-to-ship missiles, which have a range of more than 100 km.