Japan's military said the missile landed in waters outside its exclusive economic zone, while South Korea's military, which often accuses the North of exaggerating its capabilities, said it travelled more than 700 kilometres.
North Korea in recent years has added mines, anti-tank barriers and other front-line fortifications, raising concerns in the South about the growing presence of North Korean soldiers near the border.
The northern and southern boundaries of the zone are among the world's most heavily fortified frontiers, and landmine incidents have previously heightened tensions between the two Koreas.
Pyongyang, which supports Russia's invasion of Ukraine, has helped staff and arm its forces. The UN says up to 25,000 North Koreans assemble drones in Russia, with most of their pay seized by Kim Jong-un's regime.
North Korea has legally enshrined its status as a nuclear-armed state, with its leadership repeatedly declaring the country's atomic arsenal permanent and irreversible.