The Self-Defense Forces are considering joining the United States in maritime air patrols in the South China Sea in response to China's increasingly assertive pursuit of territorial claims, a Japanese and a U.S. source familiar with the discussions said.

News of the deliberations came as Japan and the United States unveiled new defense guidelines during a visit to Washington by Prime Minster Shinzo Abe, reflecting his plans for Japan to take on a wider security role beyond the direct defense of its home islands.

While no concrete plans had yet been formulated, Japan could join U.S. patrols in the South China Sea, or operate patrols in rotation from the Japanese island of Okinawa on the edge of the East China Sea, the Japanese source said, speaking on condition of anonymity.