Secretary of State Rex Tillerson called Friday for new economic sanctions on North Korea and other "painful" measures over its nuclear weapons program, as the Trump administration warned that it would take military action if diplomacy failed.

"Failing to act now on the most pressing security issue in the world may bring catastrophic consequences," Tillerson said during an unusual high-level session of the U.N. Security Council called to review what the Trump administration calls its most dire national security concern. "The more we bide our time, the sooner we will run out of it."

Tillerson's push at a special session of the Security Council came as the Trump administration said it is willing to bargain directly with North Korea over ending its nuclear weapons program, but under strict conditions that make talks unlikely anytime soon.

Ahead of the diplomatic effort at the United Nations, President Donald Trump said direct conflict is possible. "There is a chance that we could end up having a major, major conflict with North Korea. Absolutely," Trump told Reuters in an interview this week. "We'd love to solve things diplomatically, but it's very difficult."

Hours after the U.N. meeting, North Korea fired another missile early Saturday local time, but it exploded within seconds of being launched, American and South Korean defense officials said. "The missile did not leave North Korean territory," U.S. Pacific Command spokesman Cmdr. Dave Benham said in a statement. The launch underscored North Korea's determination to show its defiance of international pressure.

Trump took to Twitter to reiterate his expectation that Chinese President Xi Jinping will use his leverage to make North Korea stop its weapons activities.

"North Korea disrespected the wishes of China & its highly respected President when it launched, though unsuccessfully, a missile today. Bad!" Trump tweeted.

In the most-detailed explanation to date of the Trump administration's emerging policy for dealing with North Korea, Tillerson told the Security Council on Friday that U.S. urgency is driven by the current nuclear threat to allies South Korea and Japan as well as the likelihood that North Korea will soon be able to strike the United States.

"All options for responding to future provocation must remain on the table. Diplomatic and financial levers of power will be backed up by a willingness to counteract North Korean aggression with military action if necessary," Tillerson said.

"We much prefer a negotiated solution to this problem," he added. "But we are committed to defending ourselves and our allies against North Korean aggression."

The effect of both Trump's and Tillerson's remarks is to present a willingness to negotiate with North Korea that surprised and pleased diplomats the United States needs for any new joint effort at the United Nations or elsewhere. At the same time, the administration reiterated that it would act alone if necessary.

At issue is North Korea's simultaneous effort to perfect a nuclear warhead that could be delivered far from its shores and to develop missiles with a range long enough to be a threat to the United States. Analysts think North Korea, if undeterred, could have that capability within a few years - likely during Trump's first term in office. North Korea already possesses missiles able to threaten U.S. allies South Korea and Japan, as well as other Asian neighbors.

The top U.S. diplomat said new economic penalties should come on top of scrupulous enforcement of existing sanctions, and he was bluntly critical of nations that look the other way as North Korea tries to evade the heavy yoke of sanctions the Security Council has already applied.

He asked for a halt to imports from North Korea, especially shipments of coal, and an end to a guest-worker program that provides cheap labor for other countries and earns hard currency for Pyongyang. Tillerson also asked other countries to suspend or downgrade diplomatic relations with the communist state, alleging that the regime of Kim Jong Un abuses diplomatic privileges to support illicit missile and nuclear programs.

In blunt terms, Tillerson said North Korea is unlikely to give up its weapons or change its bellicose behavior under current sanctions and diplomatic condemnations. He said new economic penalties are necessary, as well as more vigorous enforcement of existing sanctions that he said North Korea has found ways to evade.

"I urge this council to act before North Korea does," Tillerson said. "We must work together to adopt a new approach and impose increased diplomatic and economic pressure on the North Korean regime."

In a clear warning to North Korean ally China, Tillerson said nations that help North Korea evade sanctions "discredit this body."

Tillerson noted that China accounts for 90 percent of North Korea's foreign trade, giving it unique economic leverage.

He said the United States and China have had productive discussions about North Korea, and the new U.S. willingness to negotiate with North Korea is partly in deference to China's long insistence that the only way to lessen tension is through direct talks.

"The United States also would much prefer countries and people in question own up to their lapses and correct their behavior themselves, but we will not hesitate to sanction third-country entities and individuals" that help North Korea go around sanctions, Tillerson said.

Although the council did not vote on new sanctions or other measures Friday, the Trump administration hoped for a show of force, with the full council, including China, Russia and the United States, uniting to air concerns about North Korea's behavior.

Chinese Foreign Minister Wang Yi told the council that diplomacy is not hopeless, and he said China cannot be expected to rein in North Korea on its own.

"The state of affairs on the Korean Peninsula is not caused by any single party, nor is it reasonable to ask any party to take sole responsibility," Wang said via an interpreter.

"We call upon all parties, especially those directly concerned - DPRK and the U.S. - to demonstrate sincerity for dialogue and restart dialogue," Wang said, using the abbreviation for the North's formal name, the Democratic People's Republic of Korea. "China will be open to all useful proposals from the parties."

U.N. Secretary General António Guterres, who joined Tillerson and foreign ministers from countries that sit on the decision-making council, condemned what he called North Korea's repeated violations of the body's resolutions over nuclear and missile testing and development.

"I am alarmed by the risk of a military escalation in the region, including by miscalculation or misunderstanding," Guterres said.

The U.N. Security Council session Friday comes at a particularly tense time in relations between North Korea and the United States, with the Trump administration sending warships to the region in a show of force against Kim's regime.

This week, North Korea conducted large-scale artillery drills, showing off conventional weaponry that can easily reach South Korea's capital, Seoul, the center of a metropolitan region of about 25 million people.

A North Korean propaganda outlet released a video clip Thursday showing a simulated attack on the White House and declaring that the ability to destroy the United States "is in our sights."

"North Korea must understand that respect will never follow recklessness," Tillerson said Friday. "North Korea must take concrete steps to reduce the threat that its illegal weapons programs pose to the United States and our allies before we can consider talks."

The last round of direct talks, initiated in 2003 and involving the United States, China and other nations, produced no rollback of the North Korean program. Last month, during his first trip to South Korea, Japan and China as secretary, Tillerson declared that the "era of strategic patience" that included those talks was over and that "all options" were on the table.

Trump has been urging China to pressure North Korea and has warned that his administration will act if Beijing does not.

China supports talks and has long argued that although it also wants to rid North Korea of nuclear weapons, it cannot persuade the country to give them up without direct assurances from the United States.

Tillerson offered some Friday, telling the council that the United States is not seeking "regime change" to topple the Kim dynasty.