"We have nothing to say about the report," said a Defense Agency spokesman.
The influential liberal daily, Asahi Shimbun, said the United States has asked Japan for permission to place a Ground Based Radar (GBR) in Japan, which can be used to detect intercontinental ballistic missiles (ICBMs) that may be aimed at the United States.
The radar could also be used to guide interceptor missiles to destroy incoming enemy missiles, the Asahi said, without citing its sources.
The Defense Agency would ask the United States for details about the radar and would assess its compatibility with Japanese radar systems, the Asahi said.
The requested placement of such a radar might not be covered by the Japan-US security pact, under which Japan provides military facilities to US forces to defend Japan and to stabilise the Far East region, but not to defend the US mainland, the Asahi said.
Washington was making similar requests to Britain and Denmark, the Asahi added.
The report came as Japan plans to deploy an anti-missile system consisting of the seaborne Standard Missile 3 (SM-3) and the land-based Patriot Advanced Capability 3 (PAC-3) before March 2008.
SM-3s intercept ballistic missiles when they reach their highest point outside of the atmosphere and then PAC-3 missiles are used to take out the missiles that have escaped SM-3 attacks.
Japan has rushed to build up a missile defense system since North Korea fired a suspected Taepodong missile over the Japanese mainland and into the Pacific in 1998, unnerving the region and the world.