Grave moment’: end of US-Russia nuclear pact comes at worst possible time, UN chief warns

The collapse of the last remaining nuclear arms control agreement between the United States and Russia has created what the United Nations secretary-general has called a “grave and dangerous moment” for global security, warning that the timing could not be worse amid escalating geopolitical tensions and ongoing conflicts.
Speaking to reporters at UN headquarters, Secretary-General António Guterres expressed deep concern over the expiration of the New START treaty, which for more than a decade limited the number of deployed strategic nuclear warheads and provided verification measures between the world’s two largest nuclear powers.
“The end of this agreement removes a vital pillar of international security at a time when trust is eroding and confrontation is rising,” Guterres said. “This is happening at the worst possible moment for humanity.”
A Pillar of Arms Control Falls
The New START treaty, signed in 2010, capped the number of deployed nuclear warheads and delivery systems on both sides and allowed for on-site inspections to ensure compliance. It was the last surviving remnant of Cold War-era arms control frameworks that once governed U.S.–Russian nuclear relations.
Previous treaties such as the Intermediate-Range Nuclear Forces (INF) Treaty and the Anti-Ballistic Missile Treaty had already collapsed in recent years, leaving New START as the final mechanism restraining the world’s two biggest nuclear arsenals.
With its expiration, there are now no legally binding limits on the number of strategic nuclear weapons either country can deploy.
“This is uncharted territory,” said a senior arms control expert based in Geneva. “For the first time in decades, there are no formal constraints on the two nations that together possess nearly 90 percent of the world’s nuclear weapons.”
Worsening Global Climate
The end of the pact comes amid heightened hostility over the war in Ukraine and rising tensions between NATO and Moscow. Military exercises, nuclear rhetoric, and the suspension of diplomatic channels have contributed to fears of miscalculation.
Guterres warned that the erosion of arms control increases the risk of misunderstanding and accidental escalation. “When communication breaks down and verification disappears, suspicion fills the vacuum,” he said. “That is how catastrophes begin.”
Western officials argue that Russia’s actions in Ukraine and its suspension of participation in arms inspections undermined the treaty’s foundations. Moscow, in turn, has accused Washington of using arms control mechanisms for political pressure while expanding NATO’s military presence near Russian borders.
Despite these accusations, analysts note that the treaty had largely continued to function even during periods of tension, serving as a stabilizing force.
“The genius of arms control is that it works precisely when relations are bad,” said a former U.S. negotiator. “It creates predictability when politics cannot.”
UN Alarm Over Nuclear Risks
The UN chief’s warning reflects growing anxiety across the international community about a renewed nuclear arms race. Several countries are modernizing their arsenals, and new technologies such as hypersonic missiles and artificial intelligence are complicating deterrence strategies.
Guterres said the world is now facing “a return to nuclear brinkmanship” at a time when cooperation is needed to address climate change, pandemics, and global inequality.
“We are witnessing the dismantling of safeguards built over decades,” he said. “The cost of failure will be measured in human lives.”
The UN has repeatedly called for renewed dialogue between Washington and Moscow, urging both sides to recommit to arms control and transparency.
Diplomatic Deadlock
Efforts to negotiate a replacement treaty have stalled. Officials on both sides blame political conditions and lack of trust for the failure to begin serious talks.
A U.S. State Department spokesperson said Washington remains open to discussions on a new framework but insists that Russia must first demonstrate willingness to abide by international norms.
Russian officials, meanwhile, have linked any future agreement to broader security concerns, including NATO expansion and U.S. missile defense systems.
“There is no appetite for compromise right now,” said a European diplomat involved in disarmament talks. “The relationship is defined by confrontation, not cooperation.”
China’s growing nuclear arsenal has also complicated negotiations. U.S. officials argue that future arms control must include Beijing, while China maintains that its stockpile is far smaller than those of the United States and Russia and does not require formal limits.
Public and Expert Reaction
Peace groups and nuclear watchdog organizations described the end of the treaty as a historic setback. Several called for urgent international pressure to restart negotiations.
“This is a dark day for arms control,” said a representative of a global disarmament campaign. “Without rules, the temptation to expand arsenals will grow.”
Military analysts also warned that the absence of verification mechanisms could lead to worst-case assumptions on both sides, increasing the likelihood of arms buildups and aggressive posturing.
“When you cannot inspect, you imagine the worst,” said one security scholar. “That fuels competition and fear.”
A Call for Leadership
Guterres urged world leaders to act before the situation deteriorates further. He called for renewed dialogue, confidence-building measures, and recommitment to the principles of non-proliferation.
“The alternative is a world with more nuclear weapons, less trust, and more danger,” he said. “This is not the future humanity deserves.”
While there is little sign of immediate progress, diplomats say back-channel contacts may continue quietly. Some hope that future political changes could reopen the door to negotiations.
For now, however, the expiration of the U.S.–Russia nuclear pact marks a profound shift in global security.
As the UN chief warned, the disappearance of the last guardrail against nuclear escalation comes at a moment when the international system is under strain from war, rivalry, and uncertainty. Whether new safeguards can be built in time may determine the shape of global stability for decades to come.