Tokyo: Japan is considering introducing a new type of missile defence system to counter airborne attacks, notably from North Korea, a local newspaper said Sunday.

Japan has two types of defence against airborne attacks — the warship-installed Standard Missile 3 (SM-3) and Patriot Advanced Capability 3 (PAC-3), a surface-to-air missile that tracks and hits incoming targets.

It plans to complete the shield by early 2011, deploying the PAC-3 missiles at 11 bases and setting up SM-3 missiles on several warships.

But the two systems still will not be enough to cover the nation’s territory completely, the Mainichi daily said, without citing sources.

The Japanese defence ministry is considering introducing another surface-to-air missile, the US-developed Terminal High Altitude Area Defence (THAAD) system, in addition to SM-3 and PAC-3, the newspaper said.

While the PAC-3 has a range of about 20 kilometres (12.4 miles), a THAAD interceptor can cover more than 100 kilometres, making it possible to defend the entire nation if deployed at three to four bases, the report said.

Despite its pacifist constitution and heavy reliance on the US military for protection, Japan has the world’s seventh biggest military spending in 2008, according to the Stockholm International Peace Research Institute.

Washington and Tokyo have been working jointly to install a shield against attacks from North Korea, which fired a missile over Japan’s main island in 1998 and tested an atom bomb in 2006.

North Korea on Saturday launched seven ballistic missiles — which it is banned from firing under UN resolutions — into the Sea of Japan (East Sea) in an act of defiance apparently timed for the US Independence Day holiday.