Nuclear-armed North Korea has warned Tokyo against "imminent self-destruction" for siding with Washington, as tensions soar after Pyongyang fired a missile over Japan.
The North set off global alarm Tuesday when it fired an intermediate-range missile over the Asian island nation, triggering condemnation from world leaders including the US and Japan.
Japanese Prime Minister Shinzo Abe denounced the launch as an "unprecedented, serious and grave threat" and agreed with US President Donald Trump to "further strengthen pressure against North Korea".
The North's official KCNA news agency decried the former colonial power in a commentary, saying: "Japan has now come out with its sleeves rolled up in supporting its master's anti-DPRK war moves."
The allies' "military nexus" had become a "serious threat" to the Korean peninsula and Japan was "unaware" it was "accelerating self-destruction", the statement late Wednesday said.
It made a specific reference to US forces being based in Hokkaido - the island that the North's missile flew over.
"The DPRK's toughest countermeasures include a warning to Japan going wild, being unaware of its imminent destruction," and blindly following the US, it added.
Pyongyang has warned of more similar tests to come.
The authorities in North Korea are highly nationalistic and promote resentment of the US and Japan as part of their claim to legitimacy.
KCNA said earlier that the missile launch was timed to mark the 107th anniversary of the "disgraceful" Japan-Korea treaty of 1910, under which Tokyo colonised the Korean peninsula.