The countries do not have formal diplomatic relations, and Pyongyang frequently criticises Tokyo over its colonial rule of the Korean peninsula. SEOUL: North Korea accused Japan of a "grave provocation" on Wednesday (Apr 15) after Tokyo laid out its opposition to Pyongyang's nuclear programme in an annual diplomatic paper. The countries do not have formal diplomatic relations, and Pyongyang frequently criticises Tokyo over its colonial rule of the Korean peninsula, which ended with World War II.