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 Japanese-administered Senkakus, 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.

File photo taken in September 2012 shows the Senkaku Islands in the East China Sea. (Kyodo)

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

North Korea has been launching ballistic missiles at an unprecedented pace since the start of this year including one that flew over Japan.

The missile Japan is hoping to develop contains a number of features that will make it difficult to intercept.

After it is fired from a mobile launcher, the warhead separates at high altitude and travels on an irregular trajectory before gliding at supersonic speed toward its target.

Research on the missile began in fiscal 2018, and current prototypes have a range of several hundred kilometers. These are expected to be mass produced from next fiscal year and deployed in fiscal 2026. The improved version will extend the range beyond 1,000 km.

The move comes as Japan is trying to develop its own standoff missiles -- capable of attacking enemy vessels from outside their firing range -- that can be launched not just from land but also from ships and aircraft.

As such, it is planning to extend the range of the Ground Self-Defense Force's Type-12 surface-to-ship guided missiles.

In addition, Japan is considering buying U.S.-developed Tomahawk cruise missiles, which have a range of up to 2,500 km and can travel relatively low to the ground, to bolster its deterrence capacity, according to government officials.