North Korea's military has launched a missile off its eastern coast and towards the sea, South Korea's Joint Chiefs of Staff reported on Sunday.
"North Korea fires unidentified ballistic missile towards East Sea," South Korea said, referring to what is also called the Sea of Japan.
It was not yet clear how far the missile flew, but Japan's Coast Guard said an "object, potentially ballistic missile, launched from North Korea," had already fallen.
Japanese broadcaster NHK said that the missile landed outside of the country's exclusive economic zone — a maritime region that surrounds the Japanese landmass.
Tensions rising after spy satellite launch
The missile launch is the first since Pyongyang test-fired its Hwasong-18 missile in mid-December.
The solid-fueled intercontinental ballistic missile was designed to reach the US mainland and is the country's most advanced long-range weapon. It was not clear whether Sunday's launch was also a Hwasong-18.
The missile launch comes after the north launched several rounds of artillery fire in exercises close to a disputed border on the Korean peninsula.
Tensions between the two neighbors has been ramping up after Pyongyang launched a military spy satellite in November and pledged to expand its nuclear arsenal.
North Korea points to what it calls US hostility to justify its own military maneuvers.
Pyongyang has also been upping its rhetoric, with leader Kim Jong Un calling South Korea "our principal enemy" earlier this week, and threatening to annihilate its southern neighbor if provoked.
Experts have warned that Pyongyang could increase its test-firing of ballistic missiles in the run up to South Korea's parliamentary elections in April and the US presidential elections in November.