North Korea Irate Over Japanese Military Upgrades

Japanese Maritime Self-Defense Force ships sail in formation during naval exercises off Sagami Bay, Japan, on Oct. 22, 2006. Koichi Kamoshida/Getty Images

North Korea is fuming over news Japan is making a series of investments in its self defense force that give it better offensive capabilities in the face of threats from North Korea.

Among the upgrades, Japan could convert its helicopter carriers into aircraft carriers with the purchase of F-35B vertical-takeoff strike fighters.