The efforts have taken on greater urgency in the face of a possible North Korean long-range missile launch but officials said the initiatives have been under discussion for some time as part of a broader realignment of US forces in Japan.

General Henry "Trey" Obering, head of the US Missile Defense Agency, said Friday that an X-band radar has been located in Japan as part of a network of forward deployed missile defense sensors that also includes US Aegis destroyers.

The site selected for the so-called Forward Based X-band Transportable (FBX-T) radar is opposite North Korea in northeastern Japan at an air base near the village of Shariki.

The Missile Defense Agency said Monday data gathered by the radar will be shared between US and Japanese forces, and "will support capabilities to intercept hostile missiles."

"The radar will be capable of detecting ballistic missiles early in their flight and will provide precise tracking information for use by the combatant commanders," the agency said.

"This approach provides overlapping sensor-coverage, expands potential battle space, and complicates an enemys ability to penetrate the defense system," the agency said.

Testing of the radar could begin as early as this week, a defense official said.

Japan was stunned in 1998 when North Korea fired a long-range Taepodong missile in a surprise test, and tensions again are on the rise over North Korean preparations for a possible Taepodong-2 launch.

Japan, which still has no missile defense system, has agreed in principle to the deployment of US Army Patriot Advanced Capability-3 missile defense systems at US military installations to protect US forces.

Neither side would say when the PAC-3 missile defense batteries will deploy.

The Yomiuri Shimbun, citing unnamed government sources, said Washington told Tokyo at a June 17 working-level meeting in Hawaii of the plans to install three to four Patriot missiles at its Okinawa bases.

An additional 500 to 600 US troops also would be deployed along with the PAC-3 missiles by the end of the year, Japan's top-selling daily said.

Tokyo plans to accept the deployment despite expected concerns in Okinawa, which hosts 75 percent of US military facilities in Japan, it said. "Whereas the technical requirements of the FBX-T necessitated selection of the Shariki site, where the US does not have a base, the US will not require additional facilities and areas for deployment of our PAC-3 capabilities," said Lieutenant Colonel Brian Maka, a Pentagon spokesman.

"But we still have considerable work to do with the government of Japan before we can be more specific about a final site for this deployment," he said.

"Japan and the United States are in talks," a Japanese Defense Agency spokesman said in Tokyo. "But no details have been finalized and they can't be confirmed now because the talks are still ongoing."

Japan Says Unclear Whether North Korea korea Is Fuelling Missile

In other news from Japan, the nation's Defence Agency chief said Monday it was still unclear whether North Korea is fuelling a long-range missile which has been spotted at a launch site.

"It appears to be true that a missile has been set at a launch site, but it is still unclear if fuel has been loaded or not," Fukushiro Nukaga said in a speech in the southern city of Osaka.

US and Asian officials have said North Korea is preparing to launch a Taepodong-2 missile, which could hit Alaska or possibly Hawaii, amid a standoff over the communist state's nuclear program.

US National Security Adviser Stephen Hadley said last week it was "hard to tell" whether the North was fuelling the missile.

North Korea fired a Nodong missile in 1993 and five years later launched a Taepodong-1 over Japan into the Pacific Ocean.

The North, which declared last year that it had nuclear weapons, is widely seen as using the launch threat to put pressure on the United States amid a stalemate in nuclear disarmament talks.

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