North Korea has fired an intercontinental ballistic missile (ICBM) but it failed mid-flight, says the South Korean military.
The ICBM launch, the North's seventh this year, sparked an alert in Japan - but fell short, landing in the sea.
Tensions are escalating amid fears the North will soon conduct a nuclear test.
On Wednesday both Koreas fired missiles near each other's waters. The exchange saw the most number of missiles launched by the North in a single day.
North Korea's multiple launches comes as the US and South Korea are staging their largest-ever joint air drills, which Pyongyang has strongly criticised as "aggressive and provocative".
On Thursday North Korea fired a long-range missile at around 07:40 local time (23:40 GMT), according to a statement from South Korea's Joint Chiefs of Staff. A source confirmed with the BBC that it was an ICBM.
It flew for about 760km (472 miles) and reached a height of around 1,920 km.
But the launch was "presumed to have ended in failure", South Korea's military said.
Pyongyang also fired two short-range ballistic missiles.