North Korea has branded Japan’s PM Shinzo Abe an “imbecile” and “political dwarf”, accusing him of mislabelling its latest weapons test.
Mr Abe condemned the North for “repeated launches of ballistic missiles” after two projectiles were fired on Thursday.
But the North insisted it was testing a “super-large multiple-rocket launcher”.
On Saturday, state media said Japan “may see what a real ballistic missile is in the not distant future”.
North Korea is banned from firing ballistic missiles under UN Security Council resolutions.
The country is under various sets of sanctions over its missile and nuclear programs. Lifting the sanctions has been a key aim of the North in talks with the US – Japan’s ally – but these have stalled since a summit between its leader Kim Jong-un and President Donald Trump broke down in February.