The United States wants Japan to either provide full access to radar data collected by the Self-Defense Forces or allow the U.S. military to build a radar station in Japan as part of information-sharing for missile defense, a senior Defense Agency official said Monday.

The request was made in mid-January in the runup to the deployment of the U.S.-prepared missile defense system in Japan later this year.

Tokyo decided in December to introduce a defense shield featuring U.S.-made missiles in fiscal 2004 to defend against possible North Korean attacks.