SEOUL -  North Korean leader Kim Jong-Un said his country had achieved full nuclear statehood on Wednesday after a groundbreaking missile test, in a challenge to US President Donald Trump who responded with promises of "major sanctions".

Pyongyang on Wednesday tested its third intercontinental ballistic missile (ICBM) -- which it claimed was capable of striking anywhere in the United States -- snapping a two-month pause in activity.

"Just spoke to President XI JINPING of China concerning the provocative actions of North Korea," Trump tweeted. "Additional major sanctions will be imposed on North Korea today. This situation will be handled!"

During his call with Xi, the White House said Trump urged Beijing to use "all available levers" to press the hermit state.

Trump, who last week announced fresh sanctions on Pyongyang and returned it to a US list of state sponsors of terror, had been opaque in his immediate response, saying "we will take care of it", as the UN Security Council agreed to meet in an emergency session.

France's United Nations Ambassador Francois Delattre said there should be a "tightening of the sanctions," in response to the latest test. Before assuming office, Trump had dismissed a North Korean statement declaring it was close to developing a nuclear weapon capable of hitting the US, vowing "it won't happen!"

North Korean state television brought out Ri Chun-Hee, a star presenter who only appears for significant developments, to announce the landmark. "Kim Jong-Un declared with pride that now we have finally realised the great historic cause of completing the state nuclear force, the cause of building a rocket power," she said.

Wednesday's missile was more sophisticated than any previously tested, state media said. "The ICBM Hwasong-15 type weaponry system is an intercontinental ballistic rocket tipped with super-large heavy warhead which is capable of striking the whole mainland of the US," the North's official news agency KCNA said.

Pyongyang said the missile reached an altitude of 4,475 kilometres (2,800 miles) and splashed down 950 kilometres from its launch site. At least one Western expert said the missile's lofted trajectory suggested an actual range of 13,000 kilometres -- enough to hit every major US city.

Russia called the launch "provocative" and China, North Korea's sole major ally and diplomatic protector, expressed "grave concern and opposition".

Beijing once again pressed its proposal that the North stop missile and nuclear tests in exchange for a freeze of US military exercises. Washington has repeatedly rejected the suggestion.

David Wright, an arms control expert and co-director at the Union of Concerned Scientists, said the flight parameters of Wednesday's test pointed to a missile with "more than enough range to reach Washington DC, and in fact any part of the continental United States".

While Pyongyang has yet to prove its mastery of the re-entry technology required to bring a warhead back through the Earth's atmosphere, experts believe it is at least on the threshold of developing a working intercontinental nuclear strike capability.

A US official, speaking on condition of anonymity, told AFP that the US has not changed its assessment that its missile defense systems can stop a North Korean missile attack, though the guarantee cannot be ensured indefinitely.

"I don't think they could successfully nuke the US at this time," the official said. "There is a general sense we can stop whatever North Korea has right now. For the future, I don't know."

The United States has spent decades and billions of dollars developing technologies to stop an incoming ballistic missile, and Congress is throwing billions more dollars at the Pentagon to step up its efforts.

North Korean state media said its weapons "would not pose any threat to any country and region as long as the interests of the DPRK are not infringed upon. This is our solemn declaration."

Melissa Hanham, senior research associate with the East Asia Nonproliferation Program of the Middlebury Institute, said this could indicate a diplomatic off-ramp from the present standoff with the US. "Perhaps this is an out," she wrote on Twitter. "A way to say they've achieved what they want, as long as we treat them the way they want to be treated."