North Korea has fired a suspected ballistic missile designed to be launched from a submarine, South Korea's military said.
The apparent move continues a provocative streak in weapons demonstrations that may culminate with a nuclear test in the coming weeks or months, experts believe.
South Korea's joint chiefs of staff said the launch occurred from waters near the eastern port city of Sinpo, where North Korea has a major shipyard building submarines.
It was not revealed how far the missile flew and it is also unclear whether the launch would have involved an actual submarine or an underwater test platform.
Japan's defence ministry also confirmed the launch, but it did not immediately release flight details.
The Japanese Prime Minister Fumio Kishida ordered officials to prepare for all "unforeseeable situations" and secure the safety of aircraft and ships, but there were no immediate reports of damage.
This launch was apparently North Korea's first demonstration of a submarine-fired ballistic system since October last year when it test-launched a new short-range missile from the 8.24 Yongung – its only known submarine capable of firing a missile – in what was its first underwater test launch since 2019.
The demonstration came three days after the South Korean and Japanese militaries detected the North firing a suspected ballistic missile from near its capital, Pyongyang and three days before the inauguration of South Korean President-elect Yoon Suk Yeol, who has vowed to take a tougher approach to the North's nuclear ambitions.
Watch: In March, North Korea launches first intercontinental ballistic missile in more than four years.
This latest launch was likely to be North Korea's 15th round of missile firings this year, including its first test of an intercontinental ballistic missile (ICBM) since 2017 in March that demonstrated the potential range to reach the entirety of the US mainland.
North Korea could be seen to be exploiting a favourable environment to push forward its weapons programme, with the UN Security Council divided over Russia's war on Ukraine.