For half a century, arms control treaties capped the world’s most dangerous weapons: the Nuclear Non-Proliferation Treaty limited their spread, while US-Soviet agreements from SALT to New START shrank deployed arsenals from 70,000 warheads to a fraction. Today that architecture is crumbling — the INF Treaty is dead, New START’s future is uncertain, and the NPT faces its gravest crisis. This is the story of arms control’s rise and unraveling.

What is the NPT?

The 1968 Nuclear Non-Proliferation Treaty is the cornerstone: 191 states joined, making it the most widely adhered-to arms agreement in history. Its grand bargain has three pillars — non-nuclear states foreswear weapons, nuclear states pursue disarmament, and all gain access to peaceful nuclear energy. It worked remarkably well: only four states stayed out (India, Pakistan, Israel, North Korea — which joined then withdrew), and the feared cascade of dozens of nuclear powers never materialised. But the disarmament pillar’s hollowness breeds resentment: non-nuclear states ask why the five recognised nuclear powers keep modernising arsenals while demanding others abstain.

How did the superpowers limit their arsenals?

US-Soviet arms control moved in stages. SALT I (1972) froze missile launchers; the ABM Treaty limited missile defences, preserving mutual vulnerability. START I (1991) cut deployed strategic warheads dramatically; the INF Treaty (1987) eliminated an entire class of intermediate missiles. New START (2010), capping each side at 1,550 deployed strategic warheads with on-site inspections, was the last standing pillar. Verification — satellites, inspections, data exchanges — was the genius: enemies learned to trust but verify, building habits of transparency that stabilised rivalry.

Why is the architecture collapsing?

The unraveling has multiple authors. Washington withdrew from the ABM Treaty in 2002 and the INF Treaty in 2019, citing Russian violations and China’s unconstrained buildup; Moscow suspended New START participation in 2023 amid the Ukraine war. The NPT’s 2022 review conference collapsed without consensus, and the Treaty on the Prohibition of Nuclear Weapons — backed by non-nuclear states but boycotted by all nine nuclear powers — deepened the divide. China’s refusal to join bilateral limits while expanding its arsenal makes any successor framework necessarily trilateral, vastly complicating negotiation.

What fills the vacuum?

Without treaties, dangers multiply.

• Arms racing: all nine nuclear powers are modernising; China may reach 1,000 warheads by 2030.
• Opacity: lost inspections mean lost transparency — adversaries assume the worst.
• New weapons: hypersonics, AI-enabled systems and space weapons have no governing rules.
• Proliferation pressure: as guarantees wobble, allies from Seoul to Warsaw debate their own bombs.
• Norm erosion: nuclear threats in Ukraine weaken the taboo underpinning restraint.

Arms control was never idealism; it was enlightened self-interest — enemies cooperating to avoid mutual suicide. Its collapse does not make nuclear war likely, but it removes the guardrails, the transparency and the habits of dialogue that kept rivalry bounded. Rebuilding them, in a three-way world, is the hardest diplomatic challenge of the decade.

India’s complicated arms-control story

India’s relationship with arms control is uniquely fraught: it refused to sign the NPT, calling it nuclear apartheid that legitimised the arsenals of five states while denying others. After the 1974 peaceful nuclear explosion drew sanctions, India built its arsenal outside the treaty, tested again in 1998, and then — through the 2008 NSG waiver and the US-India civil nuclear deal — won de facto acceptance as a responsible nuclear power without signing. New Delhi now champions disarmament rhetorically while modernising its triad, embodying the NPT’s central tension: a state that rejected the bargain yet demands its benefits.

Can arms control be rebuilt?

Any revival must solve the three-body problem: caps that include China, cover new technologies like hypersonics and AI, and survive domestic politics in Washington and Moscow. Modest steps — revived hotlines, notifications of missile tests, transparency on arsenals — could rebuild habits of restraint. Grand bargains look distant while the Ukraine war rages. But the logic that built arms control endures: even enemies share an interest in not dying together.

FAQs

What is the NPT?

The 1968 treaty, signed by 191 states, in which non-nuclear countries foreswear weapons while nuclear states pledge disarmament and all share peaceful nuclear technology.

Is New START still in force?

The treaty’s caps technically endure but Russia suspended participation in 2023, inspections have halted, and its future beyond expiry is deeply uncertain.

Why did the INF Treaty collapse?

The US withdrew in 2019 citing Russian violations; both sides then developed previously banned intermediate missiles, with China unconstrained throughout.

Source: Arms Control Association