The US on Wednesday signalled President Donald Trump's diplomatic efforts with North Korea's leader were nearing an end, and that Kim Jong-un's threats of new missile tests meant a response beyond dialogue may be necessary.
Mr Kim has warned of a spectacular “Christmas gift” if the US does not make concessions to Pyongyang by the end of the year, after almost two years of talks.
He and Mr Trump have held two summits and had a third meeting in the demilitarised zone between the two Koreas.
Those meetings have not provided progress towards a treaty or accord. With no sanctions relief coming, dialogue has stopped and North Korea resumed short-range missile testing in May.
Messages between the two countries have returned to the combative tone heard before Mr Trump began a charm offensive with the North's leader early in 2018.
Mr Kim's suggestion that a new test could be imminent has raised concern about the country's intercontinental ballistic missile programme, which could provide the technology for a nuclear warhead to reach the US.
Analysts have consistently said Mr Kim will not agree to give up the North's nuclear weapons, no matter what sanctions relief or concessions are offered.
The Trump administration, along with other countries, is demanding complete denuclearisation from North Korea, which is officially called DPRK.
With no progress evident, Kim Yong-chol, a top aide to Mr Kim, last week called the US president a “heedless and erratic old man” and condemned his “odd words and expression”.
A meeting of the UN Security Council on Wednesday, called by the US after weeks of pressure from European and other members who accuse the North of breaking UN resolutions, amounted to an admission that Mr Trump's efforts had stalled.
“Missile and nuclear testing will not bring the DPRK greater security," said Kelly Craft, US ambassador to the UN.
“We trust that the DPRK will turn away from further hostility and threats, and instead make a bold decision to engage with us.
“If events prove otherwise, we, this Security Council, must all be prepared to act accordingly.”
Ms Craft was hinting at sanctions against Pyongyang.
UN Assistant Secretary General Khaled Khiari told the council that a launch on November 28 was the 13th time North Korea had fired ballistic missiles this year.
North Korea announced on December 7 that “an important test” at the Sohae Satellite Launching Ground, on the west coast, would help to change the “strategic position of the DPRK once again in the near future”.
Military experts believe the word “strategic” refers to the North's nuclear capability and Mr Khiari said analysts had reported signs of a rocket engine test at the site in recent days.
This is sometimes a precursor to a nuclear test.
The European countries at the UN, led by Britain, France and Germany, has warned repeatedly in the past three months that North Korea's resumption of missile tests must be answered.
More than 20 have been reported this year.
The US, seeking to sustain its attempts to reach peace on the Korean Peninsula and end the North's missile activity, had until Wednesday sought to avoid a diplomatic clash with Pyongyang.
Ms Craft said the US was prepared to offer “flexibility” in fulfilling a plan for action signed by Mr Trump and Mr Kim in their first summit, in Singapore in April 2018.
But she voiced concern that the North was indicating it would test intercontinental ballistic missiles “which are designed to attack the continental United States with nuclear weapons”.
Ms Craft appeared to rule out meeting North Korea's demands for an offer in the year's final weeks.
“The United States and the Security Council have a goal – not a deadline,” she said.
“We remain ready to take action in parallel, and to simultaneously take concrete steps towards this agreement.”
China and Russia, who like the US, Britain and France are permanent members of the council and hold the power of veto, indicated that collective action on Pyongyang's nuclear programme would be difficult.
“There appears no prospect of progress” on denuclearisation, only stagnation, said Russia's ambassador to the UN, Vassily Nebenzia.
But Mr Nebenzia urged the US and North Korea to continue talks, saying: “Sanctions cannot replace diplomacy."
Britain's permanent representative to the UN, Karen Pierce, said North Korea was a threat to international peace and security, “owing to the unabated development of ballistic missile and nuclear weapons technology”.
“Since May 2019 they have tested three different types of short-range ballistic missiles, and these tests have demonstrated substantial progress for this illegal and reckless weapons programme,” Ms Pierce said.
“Further breaches of Security Council resolutions, whether they're ballistic missile launches, space launch vehicles or nuclear tests, will only harden the resolve of the council.”