North Korea fired an "unidentified ballistic missile" Sunday, Seoul's military said, days after Pyongyang announced a successful test of a solid-fuel motor for a new weapons system.
Military tensions on the Korean peninsula have risen sharply this year as Pyongyang has carried out an unprecedented blitz of weapons tests, including the launch of its most advanced intercontinental ballistic missile ever last month.
Sunday's launch came days after North Korea tested a "high-thrust solid-fuel motor", with state media describing it as an important test "for the development of another new-type strategic weapon system".
Despite heavy international sanctions over its weapons programmes, Pyongyang has built up an arsenal of intercontinental ballistic missiles (ICBMs).
All its known ICBMs are liquid-fuelled, however, and North Korean leader Kim Jong Un has placed strategic priority on developing solid-fuel engines for more advanced missiles.
Kim said this year that he wants North Korea to have the world's most powerful nuclear force, and declared his country an "irreversible" nuclear state.
The wishlist he revealed last year included solid-fuel ICBMs that could be launched from land or submarines.
- Key party meeting -
After overseeing the launch of the Hwasong-17 "monster" missile last month, Kim declared he wanted North Korea to have the world's most powerful nuclear force.
The isolated country's policy direction for next year will be laid out at a key party meeting later this month, and the official Korean Central News Agency earlier reported Kim saying that 2023 would be a "historic year".
In past years, Kim had delivered a speech every January 1, but has recently dropped the tradition in favour of making announcements at the year-end plenary meeting.
In his most recent address, which was released last New Year's Day, Kim focused on domestic affairs.
Experts say while Kim refrained from directly addressing the United States last year, he could change his tone this time around.
The United States and South Korea have warned for months this could come in North Korea conducting its seventh nuclear test.
North Korea is under multiple UN Security Council sanctions over its nuclear and missile activity since 2006.