The U.S. and Japanese militaries are looking at a site in northeastern Japan to base a radar system for a planned joint missile defense shield, the Defense Agency said Tuesday.

The two militaries are considering stationing an X-Band radar system at a Japanese air force base in Aomori, 360 miles northeast of Tokyo, said an agency spokeswoman who identified herself only by her surname, Sasaki.

Officials from the U.S. military were to go to the base Tuesday to study electromagnetic and geological conditions, Sasaki said. An agency notice said the team was expected to be at the site through Dec. 19.

Tokyo and Washington reached an agreement in October on the realignment of U.S. forces in Japan. The agreement also provided for the deployment of a missile defense system in the island nation.

The U.S. and Japan have long been working on a joint defense system. Since last year, the U.S. Navy has been patrolling the Sea of Japan, on the lookout for missiles from North Korea.

North Korea shocked Tokyo and other nations when it test-fired a missile over northern Japan in 1998. Analysts say North Korea is developing long-range missiles capable of reaching Alaska, Hawaii or perhaps the western coast of the United States.