North Korea has fired its highest-ever intercontinental ballistic missile and poses a worldwide threat, US Secretary of Defence James Mattis has said.
The missile, launched early on Wednesday, landed in Japanese waters.
It reached an altitude of 4,500km (2,800 miles) and flew 960km, according to South Korea's military.
It was the latest in a series of weapons tests that has raised tensions. Pyongyang last launched a ballistic missile in September.
It also conducted its sixth nuclear test that month. North Korea has continued to develop its nuclear and missile programme despite global condemnation and sanctions.
The UN Security Council is due to convene an emergency session to discuss the latest test.
Mr Mattis said the missile launch "went higher, frankly, than any previous shots they have taken".
The North was building "ballistic missiles that threaten everywhere in the world", he added.
US President Donald Trump was briefed while the missile was still in the air, the White House said. Afterwards he said: "We will take care of it."
The BBC's Rupert Wingfield-Hayes says estimates by Japanese and US experts suggest if fired on a normal trajectory this missile could have reached Washington DC.
That means North Korea is now very close to attaining its goal of an operational intercontinental ballistic missile that can strike anywhere in the mainland US, says our correspondent.
Wednesday's missile was launched from Pyongsong, in South Pyongan province, reported South Korean news agency Yonhap.
Japanese officials said the projectile travelled for about 50 minutes - but did not fly over Japan, as some have done in the past - and landed about 250km off its northern coast.
Japan also said it would "never accept North Korea's continuous provocative behaviour", while South Korea condemned the launch and responded with a missile exercise of its own.
The EU has called the launch a "further unacceptable violation" of North Korea's international obligations, while Britain's ambassador to the UN called it "a reckless act".
Source: BBC