It said the ballistic missile was an intermediate range Hwasong-12.
Japan and South Korea said it reached a maximum altitude of 2,000km before coming down in the Sea of Japan. Both countries have condemned the launch, the seventh test this month.
The UN prohibits North Korea from ballistic and nuclear weapons tests, and has imposed strict sanctions.
But the East Asian state regularly defies the ban, and leader Kim Jong-un has vowed to bolster his country's defences.
North Korean state news agency KCNA said the missile had been launched to "verify its accuracy". Mr Kim was reportedly not present.