North Korea fired a ballistic missile over the sea to the east of the Korean Peninsula in the early hours of Sunday, the South Korean military said.
The move comes not even 24 hours after North Korea launched three ballistic missiles on Saturday.
The short-range ballistic missile was fired around 2:50 a.m. local time (1750 GMT) from around the capital Pyongyang, South Korea's Joint Chiefs of Staff said.
The missile flew for about 400 kilometres (249 miles) before landing in the sea, Yonhap news agency said, citing the military.
U.S. Indo-Pacific Command said in a statement that though the launch did not pose an immediate threat to U.S. personnel or territory, or to Washington's allies, it highlighted the destabilising impact of North Korea's weapons programme.
Japanese Defence Minister Yasukazu Hamada has protested to North Korea over the launch, Kyodo News reported on Sunday.
The launch follows an unprecedented number of missile tests conducted by North Korea in 2022, as Pyongyang presses on with weapons development amid speculation it could test a nuclear weapon for a seventh time.
In 2022, the North also resumed testing intercontinental ballistic missiles for the first time since 2017, successfully launching the massive new Hwasong-17, which is believed to have the range to strike anywhere in the United States.
North Korean state media KCNA said on Saturday that its central party had engaged in the fifth day of a plenary session on Friday to solidify strategy, with the session expected to continue, making it the longest ever according to Yonhap. The results of the session could be known as early as Sunday.
