North Korea has fired a short-range ballistic missile over the Sea of Japan after lambasting Japan over its military build-up in the Pacific.South Korea’s Joint Chiefs of Staff (JCS) on Thursday said that “our military detected one short-range ballistic missile launched from the Wonsan area of North Korea at around 5pm (6pm AEST)”.It added that the missile was launched towards the Sea of Japan and that authorities in Seoul and Washington were analysing the missile’s exact specifications.It comes after North Korean state media on Wednesday broadcast Kim Yo-Jong - the sister of leader Kim Jong-un - saying Pyongyang’s “leadership will set up additional military options which are obviously due to Japan’s transformation”.North Korea, which since 2019 has repeatedly declared itself an “irreversible” nuclear state, featured among growing regional threats in a recent Japanese government assessment.Tokyo’s Defence Minister Shinjiro Koizumi said this week that Japan’s military needs to be boosted with a “sense of urgency and crisis”.The defence ministry declined to comment directly on Kim Yo Jong’s Wednesday diatribe but said the country’s defence capabilities “remain bare minimum” and “are not meant to threaten other countries”.Tokyo raised its military expenditure by 9.7 per cent to $62.2 billion in 2025 - equivalent to 1.4 per cent of GDP, its highest share since 1958.Following the launch, Tokyo’s defence ministry posted on X that “something that may be a ballistic missile has been launched from North Korea”, later saying there was no impact “on the areas around Japan”.Seoul has strengthened surveillance and maintained readiness for possible additional launches while sharing information with its security allies the United States and Japan.South Korea and the United States are expected to carry out their annual Ulchi Freedom Shield military exercises, aimed at containing the nuclear-armed North, later this month.North Korea has always been infuriated by such joint drills, decrying them as rehearsals for invasion.Under the South Korea-US combined defence posture “our military is maintaining the capability and readiness to respond overwhelmingly to any provocation”, Seoul’s JCS said Thursday.‘New militarism’ North Korea has deepened its economic and military ties with Russia, supplying troops and munitions for Moscow’s war in Ukraine in exchange for financial support, food, energy and military technology, analysts say.Some experts said Thursday’s launch could have been intended to test weapons before Kim Jong-un’s expected visit to Russia this year.“Before heading to Russia, Kim may have wanted to demonstrate that Pyongyang had already tested these missile systems and achieved satisfactory results,” Ahn Chan-il, a North Korean-born researcher, told AFP.“If the trip materialises, Kim is very likely to showcase them to Russia or seek to export them.”Japan’s defence ministry declined to comment directly on Kim Yo Jong’s Wednesday diatribe but said the country’s defence capabilities “remain bare minimum” and “are not meant to threaten other countries”.Tokyo raised its military expenditure by 9.7 per cent to $62.2 billion in 2025 - equivalent to 1.4 per cent of GDP, its highest share since 1958.China, a key ally of North Korea, has also recently expressed alarm at what it sees as “new militarism” by Japan.South Korea’s President Lee Jae Myung has reversed the stance of his predecessor since taking power in Seoul in June 2025, offering nuclear-armed Pyongyang talks without preconditions.The hermetic leadership of North Korea has yet to respond to his repeated offers.