The National Police Agency has decided to arm police forces across Japan with 1,000 automatic rifles to guard important facilities -- including the Prime Minister's Official Residence and the U.S. Embassy -- against possible terrorist attacks, NPA sources said Saturday.

One thousand rifles are necessary to arm members of riot squads at Japan's 47 prefectural police headquarters, which at present only have a small number of automatic rifles, they said.

The NPA envisions purchasing the rifles by the end of the year and distributing them by the end of next March after riot squad personnel are trained.