Japan is planning to step up maritime security around the Senkaku Islands in the East China Sea.
Government members on Monday released a draft of a 5-year maritime plan.
The document refers to sightings of foreign vessels conducting marine research without approval in Japanese waters. It says the government will use domestic law to deal with such incidents.
The plan also says Japan will monitor and protect its key remote areas.
Ground Self-Defense Force troops are to be deployed in the country's westernmost island of Yonaguni, Okinawa Prefecture.
The Defense Ministry is also planning to install mobile-radar systems from the Air Self-Defense Force on the island.
The plan also covers exploitation of natural gas from methane-hydrate deposits in the sea bed. Officials will spend 3 years surveying quantities. They hope to begin commercialization of the resource around 2018.
The cabinet will decide on the draft in the next few weeks.