North Korea fired a suspected ballistic missile designed to be launched from a submarine on Saturday, South Korea’s military said, apparently continuing a provocative streak in weapons demonstrations that may culminate with a nuclear test in the coming weeks or months.

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, but it didn’t immediately say how far the missile flew. It also wasn’t clear whether the launch would have involved an actual submarine or an underwater test platform.

Japan’s Defense Ministry also confirmed the launch, but it didn’t immediately release flight details.

The 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 launch came three days after the South Korean and Japanese militaries detected the North firing a suspected ballistic missile from near its capital, Pyongyang, on Wednesday, and three days before the inauguration of South Korean President-elect Yoon Suk Yeol, who has vowed to take a tougher approach over the North’s nuclear ambitions.