North Korea says it has successfully tested its first long-range "intercontinental" missile. If confirmed, the intercontinental ballistic missile (ICBM) could potentially have the range to reach the US mainland.
The US said the missile that landed in the Sea of Japan on Tuesday was of intermediate range and did not pose a threat to North America.
North Korea has increased the frequency of its missile tests, raising tensions.
An announcement on North Korea state television said a Hwasong-14 missile was tested on Tuesday, overseen by leader Kim Jong-un.
It said the projectile reached an altitude of 2,802km (1,731 miles) and flew 933km before hitting a target in the sea.
A statement on the official KCNA news agency said North Korea was now "a full-fledged nuclear power that has been possessed of the most powerful inter-continental ballistic rocket capable of hitting any part of the world".
It would enable the country to "put an end to the US nuclear war threat and blackmail" and defend the Korean peninsula, it said.
While Pyongyang has appeared to have made progress, experts believe North Korea does not have the capability to accurately hit a target with an ICBM, or miniaturise a nuclear warhead that can fit on to such a missile.