In a first, North Korea said it has successfully tested a long-range nuclear-capable intercontinental ballistic missile (ICBM).
It said the missile is capable of striking anywhere in the world.
North Korean state television reported that the Hwasong-14 missile's launch was overseen by leader Kim Jong-Un.
Earlier, the US military said a North Korean ballistic missile had landed in the Sea of Japan.
South Korea investigating whether it was an ICBM
South Korea said the missile flew around 930km for about 40 minutes.
Both the US military and South Korea had earlier said it was an intermediate range missile.
South Korea's military is investigating whether it was an ICBM.
Experts said while North Korea has made progress in missile technology, it still lacks the capability to accurately field a nuclear-capable ICBM.
Missile launch comes ahead of G20 summit
The missile launch comes days ahead of a G20 meeting, where world leaders are expected to discuss how to rein in North Korea's weapons programs, which are in defiance of UN resolutions.
Japanese PM Shinzo Abe said he'll ask Chinese and Russian leaders to do more to stop Pyongyang's nuclear ambitions at the G20 summit.
Angry Trump condemns North Korea over missile launch
Following the latest launch, US President Donald Trump tweeted: "North Korea has just launched another missile. Does this guy have anything better to do with his life?" referring to North Korean leader Kim Jong Un.
"Perhaps China will put a heavy move on North Korea and end this nonsense once and for all!", he tweeted.
Can the missile really 'strike anywhere in the world'?
US-based expert David Wright said the latest North Korean missile, which is aimed at targeting America, was launched on a "very highly lofted" trajectory of over 2,800 km.
On a standard trajectory, the missile's maximum range would be 6,700km.
At that range, the missile would be able to reach the Alaska but not mainland USA which means it can't 'strike anywhere in the world.'