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One of the key non-proliferation breakthroughs of the past 30 years has been the conclusion of the 1996 Comprehensive Nuclear Test Ban Treaty (CTBT) and the end of explosive nuclear weapons testing. All of the P5 states (China, France, Russia, United Kingdom, United States) have had declared testing moratoria since signing the CTBT in 1996. Since then, India and Pakistan tested in 1998 and the Democratic People’s Republic of Korea (DPRK) – the only state definitively known to have conducted explosive nuclear tests after India and Pakistan – last did so in 2017.

But today, the longstanding norm against explosive nuclear testing is under increasing pressure. In the context of great power tensions, growing salience of nuclear weapons, and erosion of nuclear arms control and nonproliferation regimes, the risk of a return to nuclear explosive testing is higher than it has been in decades. Were states with nuclear weapons to resume explosive nuclear testing, that would accelerate a nuclear arms race and deal a severe, perhaps fatal, blow to the nuclear nonproliferation regime.

February 3, 2026 – Two days before the New START Treaty expires on February 5, 2026, the Deep Cuts Commission has released a joint statement warning of heightened nuclear risks and calling for continued restraint by the United States and Russian Federation.

The statement highlights that New START's end will leave both countries without bilateral arms control limits for the first time in decades, potentially eroding strategic stability and predictability. It urges both sides to voluntarily uphold the treaty's central quantitative restrictions and resume talks on a broader strategic stability framework, including sub-strategic weapons and missile defenses.

"Continued nuclear restraint and renewed dialogue are essential to demonstrate commitment to NPT Article VI obligations ahead of the 2026 Review Conference," the statement emphasizes.

Incidents and close military encounters between Russian and NATO air forces are nothing new - but the political context has changed in the face of full-scale war in Ukraine. Combined with an increasingly crowded European airspace, this means that ambiguity will remain a structural feature throughout the contact zone. But the frequency with which different phenomena can be mistaken for others makes this environment especially volatile: routine friction for deliberate signalling, signalling for escalation, civilian drone activity for hostile activities by foreign states. In a tense political environment with high levels of media attention, the pressure to act, and with it the risk of premature action based on faulty assessments, is magnified. Effective risk management therefore hinges on reducing these potential misreadings. Policies must help distinguish which incidents matter, why they matter, and what responses are appropriate.

This Issue Brief examines the deteriorating state of nuclear arms control and the shifting political dynamics that shape its current feasibility. It traces the erosion of traditional U.S.–Russian bilateral frameworks from their Cold War successes to today’s deep strategic confrontation rooted in post-Cold War power asymmetries, divergent threat perceptions, and rising domestic hardliners. The analysis highlights how U.S. unilateralism, Russia’s renewed military posture, and escalating tensions over missile defense, nuclear deterrence, and the war in Ukraine have undermined long-standing mechanisms for compartmentalized cooperation. As traditional instruments prove increasingly inadequate, the Brief evaluates alternative approaches, including multilateral formats and broader engagement on emerging technologies, that could contribute to stabilizing great-power relations in a more complex and contested security environment.

The New Strategic Arms Reduction Treaty (New START) reduced U.S. and Russian strategic offensive forces to levels not seen since the 1960s. It is the last remaining bilateral agreement limiting U.S. and Russian nuclear arms. While reducing the sides’ nuclear arsenals, New START and its predecessors enhanced predictability and stability in their uneasy nuclear deterrence relationship. Unfortunately, New START will expire soon, on February 5, 2026. However, without renewed action on nuclear arms control, an unconstrained three-way nuclear arms race looms.

Both presidents Donald Trump and Vladimir Putin have expressed willingnes to engage on strategic nuclear arms control. However any process faces difficult questions. Key obstacles are the ongoing war between Ukraine and Russia, the modernization of nuclear arsenals and questions of verification. This Deep Cuts Fact sheet lays out key challenges and provides policy options to avoid an unconstrained build-up.