North Korea has risked provoking a confrontation with Washington after it claimed on Tuesday to have launched its first intercontinental ballistic missile, an achievement that would be a key step towards developing a rocket capable of hitting the US.

The test-firing saw the missile fly off North Korea’s east coast for nearly 40 minutes and reach an altitude of more than 2,500km, characteristics that led analysts to give Pyongyang’s claim credibility. They said a long-range missile with such capabilities could reach Alaska.

The claim threatens to escalate tensions with President Donald Trump, who earlier vowed a test of a long-range missile “won’t happen”. US security agencies believe Pyongyang is attempting to miniaturise a nuclear weapon and increase the range of its missiles in order to threaten the US west coast.