North Korea understands that any attack on Japan is equal to one on the US itself and vice versa.General Joe Dunford, chairman of the Joint Chiefs of Staff, held talks with his Japanese counterpart at the defence ministry in Tokyo, wrapping up a regional tour during heightened tensions with North Korea.
Tokyo remains on alert against potential military provocations by Pyongyang after North Korea threatened to fire missiles towards the Pacific island of Guam, US territory, which would have flown over Japan.
"I think we made it clear to North Korea and anyone else in the region that an attack on one is an attack on both of us," Dunford told Katsutoshi Kawano, chief of staff of Japan's Self-Defense Forces.