Addressing the UN Security Council for the first time, Secretary of State Rex Tillerson called for a global campaign of pressure to force Pyongyang to change course and put a halt to its nuclear and ballistic missile programs.
"Failing to act now on the most pressing security issue in the world may bring catastrophic consequences," he warned.
Tillerson put the onus on China to use its "unique" leverage to influence its communist ally, but Beijing pushed back, arguing that it was unrealistic to expect one country to solve the conflict.
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"China is not a focal point of the problem on the peninsula and the key to solving the nuclear issue on the peninsula does not lie in the hands of the Chinese side," Foreign Minister Wang Yi told the council.
The Security Council meeting followed weeks of warnings from the US administration that it is running out of patience with Pyongyang. President Donald Trump has warned of the risk of a "major, major conflict".
"The threat of a North Korean nuclear attack on Seoul or Tokyo is real, and it is likely only a matter of time before North Korea develops the capability to strike the US mainland," Tillerson said.
"All options for responding to future provocation must remain on the table," he said.
"Diplomatic and financial levers of power will be backed up by willingness to counteract North Korean aggression with military action, if necessary."
Watch: Rex Tillerson addresses the UN Security Council
Russia and China made clear that a military response would be disastrous and appealed for a return to talks and de-escalation.
China's Wang warned "the use of force does not solve differences and will only lead to bigger disasters".
Russian Deputy Foreign Minister Gennady Gatilov told the council the military option was "completely unacceptable" and warned a miscalculation could have "frightening consequences".
A decade of sanctions
The meeting of the top UN body laid bare major differences among key powers over the way to address the North Korea crisis.
North Korea is seeking to develop a long-range missile capable of hitting the US mainland with a nuclear warhead, and has so far staged five atomic tests, two of them last year.
Over the past 11 years, the Security Council has imposed six sets of sanctions on Pyongyang - two adopted last year - to significantly ramp up pressure and deny Kim Jong-Un's regime the hard currency revenue needed for his military programs.
But UN sanctions experts have repeatedly told the council the measures have had little impact because they have been poorly implemented.
Watch: South Korea criticises North's 'vicious cycle'
Tillerson called on all countries to downgrade or sever diplomatic relations with North Korea and impose targeted sanctions on entities and individuals supporting its missile and nuclear program.
The United States is ready to impose sanctions on third countries where companies or individuals are found to have helped North Korea's military programs, he said.
Washington has repeatedly called for stronger UN sanctions, but wants China, North Korea's main trading partner and ally, to harden its approach.
In his remarks, Tillerson said China accounts for 90 percent of North Korea's trade and "has economic leverage over Pyongyang that is unique", suggesting sanctions from Beijing would have a strong impact.
Beijing has rejected calls for economic pressure on Pyongyang, fearing it could destabilise North Korea, and both China and Russia argued at the UN that sanctions alone were not the answer.
Call for talks
The Chinese foreign minister pushed Beijing's proposal for reviving talks based on a freeze of North Korea's military programs.
He said the long-standing proposal, which involves Pyongyang freezing military programs in exchange for a halt to US-South Korean annual military drills, was "reasonable and practical".
"Now is the time to seriously consider talks," said Wang.
The United States has rejected the Chinese plan and insists that North Korea first take concrete steps to show that it is ready to abandon its military programs.
Watch: China urges restraint in North Korea rhetoric
At the end of the meeting, Tillerson again took the floor and bluntly re-asserted Washington's stance.
"We will not negotiate our way back to the negotiating table. We will not reward their bad behavior with talks," he said.
The United States, Russia and China took part in six-party talks on North Korea's denuclearization from 2003 to 2009, along with Japan, South Korea and Pyongyang.
The meeting of the top UN body comes just days after South Korea received the first deliveries of equipment for a new missile defense system from the United States that China fiercely opposes.
