US president Donald Trump vowed additional "major sanctions" against North Korea on Wednesday in response to its latest groundbreaking missile test.
"Just spoke to President Xi Jinping of China concerning the provocative actions of North Korea," Mr Trump tweeted.
"Additional major sanctions will be imposed on North Korea today. This situation will be handled!"
It was not immediately clear if the sanctions would be from the US Treasury or broader UN sanctions that include China.
During his call with Mr Xi, the White House said Mr Trump called on Beijing to use "all available levers" to press North Korea.
Pyongyang on Tuesday fired what is believed to be an intercontinental ballistic missile capable of hitting Washington.
The US president has threatened North Korea with "fire and fury" if it continues to threaten the United States or its allies with work toward an ICBM capable of carrying a nuclear payload.
The latest test came after a more than two-month pause, which had prompted speculation that talks could end the nuclear standoff.
Since coming to office, Mr Trump has ratcheted up the diplomatic and economic pressure on the regime of Kim Jong-un, demanding he abandon nuclear and ballistic weapons.
As part of that effort, Mr Trump has repeatedly pressed China to break trade ties with its dependent neighbour and has applauded countries for shuttering Pyongyang's diplomatic installations, which have long been used to gather illicit finance.
Earlier this month, Mr Trump declared North Korea a state sponsor of terrorism — a symbolic move, but one which amps up diplomatic pressure on the regime.
The UN Security Council was expected to hold an emergency meeting later pm Wednesday to discuss the response to Pyongyang's latest test.
Mr Kim said on Wednesday that his country had achieved full nuclear statehood after what he said was the successful test of the new missile capable of striking anywhere in the United States.
The missile launch snapped a two-month pause in testing by the North and poses a new challenge to Mr Trump who has vowed such a capability "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.
"The great success in the test-fire of ICBM Hwasong-15 is a priceless victory won by the great and heroic people of the DPRK," she said, using the official abbreviated name for North Korea.
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 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.
Wednesday's launch was the North's third successful ICBM test.