The North says this intercontinental ballistic missile (ICBM) is its most powerful yet and completes the country's "rocket weaponry system development set".
It said the rocket was tipped with a "super-large heavy warhead" capable of hitting the whole of the mainland US. The rocket reached the highest altitude of any rocket tested by the North so far.
Last July North Korea tested the Hwasong-14 missile that demonstrated an altitude of 3,000km (1,865 miles) but there were still many voices doubting how far it would go with a warhead attached.
This test showed serious advances, although experts say more details need to emerge for more certainty.
North Korea says the rocket reached an altitude of 4,475km which would mean its range on a standard trajectory - as opposed to one that was fired as deliberately high - would be 13,000km. This would be "more than able to cover the continental United States, dependent on the weight of the mock warhead" likely to have been placed on it, Vipin Narang, associate professor of political science at MIT, told the BBC.
"There were the doubters on the range of Pyongyang's first two tests - and so they've improved it," he added.
"They have extended the range now out to a point that it is hard to credibly argue that North Korea couldn't have the US eastern seaboard within its range."
The only caveat would be the weight of the warhead. David Wright at the Union of Concerned Scientists points out in his blog that it is likely to have carried a very light mock warhead and that "means it would be incapable of carrying a nuclear warhead to this long distance, since such a warhead would be much heavier".