The monitors have provided vivid evidence of how Russia is keeping Pyongyang brimming with fuel and other goods, presumably in return for weapons that Russia can use in Ukraine.
Through the most tense encounters with President Vladimir V. Putin’s Russia over the past decade, there has been one project in which Washington and Moscow have claimed common cause: keeping North Korea from expanding its arsenal of nuclear weapons.
Now, even that has fallen apart.
On Thursday, Russia used its veto power in the United Nations Security Council to kill off a U.N. panel of experts that has been monitoring North Korea’s efforts to evade sanctions over its nuclear program for the past 15 years.
Russia’s discomfort with the group is a new development. Moscow once welcomed the panel’s detailed reports about sanctions violations and considered Pyongyang’s nuclear program to be a threat to global security.
But more recently, the panel has provided vivid evidence of how Russia is keeping the North brimming with fuel and other goods, presumably in return for the artillery shells and missiles that the North Korean leader, Kim Jong-un, is shipping to Russia for use against Ukraine. The group has produced satellite images of ship-to-ship transfers of oil, showing how the war in Ukraine has proved to be a bonanza for the North.
The apparent dismantlement of the panel, which had no enforcement power, is one more piece of evidence of how what was once a global effort to constrain nuclear proliferation has eroded rapidly over the past two years.
“It’s a remarkable shift,” said Robert Einhorn, a State Department official during the Obama administration who is now a senior fellow at the Brookings Institution.
“For much of the post-Cold War period, the United States, Russia and China were partners in dealing with proliferation challenges, especially with North Korea and Iran. They were fully on the American and European side during the Iran negotiations, and helped with North Korea during the ‘fire and fury’ period in 2016 to 2017,” he said, referring to the Obama administration’s final negotiations with the North and former President Donald J. Trump’s threats when he came to office.
In that era, Russia regularly voted for sanctions against North Korea, as did China, even while they all did a fair bit of business, and more than a little smuggling at sea and over their narrow border crossing, especially a rail bridge where the three all meet.
But as Mr. Einhorn noted, that unity has fractured with the re-emergence of great power competition. The partnership on containing nuclear threats, even from North Korea, whose nuclear facilities pose a safety challenge to both China and Russia, has vanished.
Russia is now helping North Korea evade sanctions, and neither Russia nor China is actively working to pressure Iran to slow its accumulation of enriched uranium, the critical step needed if it ever decides to build nuclear weapons.
When resolutions have come up to condemn North Korea for its constant barrage of missile tests, Russia and China have rejected them. But eliminating the “experts committee,” which began its work in 2009, cuts new territory in relieving pressure on the country.
The Russian government made no apologies for killing off the panel.
“It is obvious to us that the U.N. Security Council can no longer use old templates in relation to the problems of the Korean Peninsula,” a spokeswoman for the Russian Foreign Ministry, Maria Zakharova, was quoted by Reuters as saying. “The United States and its allies have clearly demonstrated that their interest does not extend beyond the task of ‘strangling’ the D.P.R.K. by all available means,” she added, using the abbreviation for the Democratic People’s Republic of Korea.
The committee had no great investigative powers, but it was thorough — and its findings often created headlines. It followed oil shipments, and explained what happened when ships turned off their transponders so they would not be tracked at sea. The group looked at banking relationships and luxury goods that made it to North Korea, despite sanctions passed 18 years ago. It also inspired private groups to dig deeper, explaining mysteries like how Mr. Kim got his luxury cars.
The experts were outsiders, and their findings were often not adopted. “Everything that goes into the report has to be approved by Security Council members,” Jenny Town, a North Korea expert and senior fellow at the Stimson Center, a nonproliferation think tank, noted on Friday. “So while it is an investigative body, its findings exist in a political process.”
Still, the existence of the committee gave an international, neutral imprimatur to the charges of sanctions evasion. “They have been very useful in producing some gravitas on sanctions implementation,” said Ms. Town, who is also the director of 38 North, which publishes analysis of North Korea’s capabilities and pronouncements.
The State Department denounced Russia’s decision, saying that the country had “cynically undermined international peace and security,” and declaring that “Russia alone will own the outcome of this veto: a D.P.R.K. more emboldened to reckless behavior and destabilizing provocations.”
No one is quite sure how many nuclear weapons the North Koreans have produced since the first nuclear crisis with the country, in 1994, or since it first tested a nuclear weapon in October 2006 during the George W. Bush administration.
Experts outside the government believe the arsenal is around 50 or 60 weapons now, though the estimates range from as low as 40 to as high as 100 — a reflection of how little is understood in the absence of inspections by another arm of the United Nations, the International Atomic Energy Agency.
But the biggest concern about the North is not the size of the arsenal but its intentions. Two leading North Korea experts, Robert L. Carlin, a former top intelligence official who was often involved in North Korea negotiations, and Siegfried S. Hecker, the former director of the Los Alamos National Laboratory, argued late last year that “the situation on the Korean Peninsula is more dangerous than it has been at any time since early June 1950,” when the Korean War broke out.
New declarations by North Korea, they said, make it clear the country has given up on the idea of reunification and may be preparing for a military solution to the division of the peninsula.
“Like his grandfather in 1950, Kim Jong-un has made a strategic decision to go to war,” they argued, a position many of their former colleagues in the intelligence world said was overly wrought. “We do not know when or how Kim plans to pull the trigger, but the danger is already far beyond the routine warnings in Washington, Seoul and Tokyo about Pyongyang’s provocations.”
In fact, the North’s language has changed, and it now talks more openly — as Russian officials do — about using nuclear weapons if provoked on matters large or small.
