Japan is considering extending the range of a new high-speed missile, still in the developmental stage, beyond 1,000 kilometers to better defend its remote islands including the China-claimed Senkaku Islands, government sources said Sunday.

The envisioned upgrade of the land-based, long-range missile will put China's coastal areas and North Korea within its range, at a time when Japan is ramping up its deterrence amid North Korean nuclear and missile threats and China's military assertiveness, the sources said.

The Senkaku Islands have long been a source of friction for Tokyo and Beijing, which claims the group of uninhabited islets in the East China Sea.