Key Agreements in Nuclear Arms Limitation: SALT, ABM, and INF Treaties

Nuclear weapons created a paradox during the Cold War. The United States and the Soviet Union built arsenals large enough to destroy each other many times over, yet neither could use them without inviting its own destruction. This logic of mutual destruction pushed both superpowers toward an unexpected solution: negotiating limits on the very weapons that defined their rivalry. Between the 1970s and 2010, a series of landmark agreements attempted to cap, control, and eventually reduce these arsenals. Understanding these treaties is essential to grasping how nations learned to manage the most dangerous technology ever invented.

Why arms limitation became necessary 🔗

By the late 1960s, both superpowers had accumulated thousands of nuclear warheads. The arms race had become economically draining and strategically pointless. Adding more weapons did not make either side safer because both already possessed assured second-strike capability, meaning each could survive a first attack and still retaliate devastatingly.

This situation produced the doctrine of Mutual Assured Destruction (MAD). Under MAD, peace was maintained not by trust but by the certainty that any nuclear attack would result in suicide. Arms limitation agreements emerged from a shared recognition that the race needed boundaries. The goal was never disarmament in the early stages. Instead, it was stability, predictability, and a reduced risk of accidental or escalatory war.

The SALT agreements and the ABM Treaty 🔗

The first serious attempt to restrain the arms race came through the Strategic Arms Limitation Talks (SALT). These negotiations began in November 1969 in Helsinki and produced two important documents signed by President Richard Nixon and Soviet leader Leonid Brezhnev in Moscow on May 26, 1972.

The Anti-Ballistic Missile Treaty 🔗

The first document was the Anti-Ballistic Missile (ABM) Treaty. This treaty tackled a counterintuitive but crucial problem. Defensive missile systems, which sound peaceful, were actually destabilizing. If one side could shoot down incoming missiles, it might believe it could launch a first strike and survive the retaliation. This would shatter the balance of mutual deterrence.

The ABM Treaty therefore limited missile defenses rather than offensive weapons. It restricted each side to a small number of interceptors, originally permitting two defensive sites that were later reduced to one. The two permitted sites had to be separated by a significant distance to prevent the creation of any nationwide defense shield. By keeping both nations vulnerable, the treaty paradoxically made both safer. The agreement remained a cornerstone of arms control until the United States withdrew from it in December 2001, citing the need to develop defenses against emerging threats.

The SALT I Interim Agreement 🔗

The second document was the SALT I Interim Agreement. This was a temporary five-year freeze that capped the number of intercontinental ballistic missiles (ICBMs) and submarine-launched ballistic missiles (SLBMs) on both sides. It was the first time the superpowers had agreed to limit their strategic offensive forces.

SALT I had important limitations. It froze launcher numbers but did not stop either side from improving the quality of its weapons. In particular, it failed to address Multiple Independently Targetable Re-entry Vehicles (MIRVs), a technology allowing a single missile to carry several warheads aimed at different targets. This gap meant the actual number of warheads could keep growing even with launchers capped.

SALT II and its troubled fate 🔗

Negotiators tried to close these gaps with SALT II, signed in 1979. This agreement set equal ceilings on strategic launchers and attempted to limit MIRVs. However, the treaty was never ratified by the US Senate following the Soviet invasion of Afghanistan that same year. Despite this, both nations largely observed its terms for several years, showing that even unratified agreements could shape behaviour.

The INF Treaty: eliminating an entire category 🔗

The next breakthrough was more ambitious. The Intermediate-Range Nuclear Forces (INF) Treaty, signed by President Ronald Reagan and Soviet leader Mikhail Gorbachev on December 8, 1987, broke entirely new ground.

The crisis behind the treaty began when the Soviet Union deployed SS-20 missiles in Europe in the late 1970s. These mobile missiles could strike targets across Western Europe within minutes, leaving NATO with little warning time. The United States responded by deploying its own missiles in Europe, raising tensions dramatically.

What made the INF Treaty historic 🔗

The INF Treaty required both sides to eliminate all ground-launched ballistic and cruise missiles with ranges between 500 and 5,500 kilometres. This was revolutionary for a simple reason. Previous treaties had only capped or slowed growth. The INF Treaty actually destroyed weapons and abolished an entire class of them permanently.

By the implementation deadline of June 1991, the two nations had destroyed a total of 2,692 missiles. The treaty also introduced extensive on-site inspections, allowing each side to verify the other’s compliance directly rather than relying on satellites alone. This verification system became a model for future agreements.

The end of the INF Treaty 🔗

The treaty’s success eventually unravelled. The United States formally withdrew on 2 August 2019, accusing Russia of developing a missile system that violated the agreement, an allegation that all NATO allies endorsed. Russia denied the charge and made counter-accusations. The collapse of the INF Treaty removed an important pillar of European security and raised fears of a renewed missile competition.

The START treaties: deep reductions begin 🔗

While SALT had limited weapons and INF had eliminated one category, the Strategic Arms Reduction Treaty (START) aimed to actually cut the core strategic arsenals. The word “reduction” in the name signalled a shift in philosophy from managing the arms race to reversing it.

START I 🔗

START I was signed by President George H. W. Bush and Mikhail Gorbachev on July 31, 1991, just months before the Soviet Union dissolved. It was the first treaty to mandate genuine reductions in deployed strategic arms. The agreement limited each side to 1,600 strategic delivery vehicles and 6,000 accountable warheads.

The collapse of the Soviet Union complicated matters immediately. Nuclear weapons were now spread across Russia, Belarus, Kazakhstan, and Ukraine. The Lisbon Protocol solved this by arranging for the three non-Russian states to transfer their weapons to Russia or destroy them, leaving Russia as the sole nuclear successor. When fully implemented, START I removed roughly 80 percent of all strategic nuclear weapons then in existence, a staggering achievement.

START II and SORT 🔗

START II, signed in 1993, sought even deeper cuts, aiming to lower arsenals to between 3,000 and 3,500 warheads and to ban MIRVs on land-based missiles. However, it was ratified by both countries but never successfully implemented due to political friction and disagreements over missile defense.

To keep momentum going, Presidents George W. Bush and Vladimir Putin signed the Strategic Offensive Reductions Treaty (SORT), also called the Moscow Treaty, in 2002. It limited each side to between 1,700 and 2,200 deployed warheads. SORT was notably brief and lacked detailed verification provisions, which critics saw as a weakness.

New START 🔗

The most significant recent agreement was New START, signed by Presidents Barack Obama and Dmitry Medvedev in April 2010. It set clear, verifiable ceilings: 1,550 deployed strategic warheads, 700 deployed delivery vehicles, and 800 deployed and non-deployed launchers for each side.

New START included robust verification through short-notice on-site inspections and regular data exchanges. It was notably the first treaty to allow inspectors to directly count the actual number of warheads on a given missile. The agreement was extended in 2021 to remain in force through early 2026.

The current crisis in arms control 🔗

The architecture of nuclear arms control has weakened sharply in recent years. The ABM Treaty ended in 2001, the INF Treaty collapsed in 2019, and most significantly, New START expired on 5 February 2026 with no replacement agreement in place.

This expiration is historic for a troubling reason. For the first time in roughly half a century, there are no legally binding limits on the world’s two largest nuclear arsenals. Russia proposed in September 2025 that both sides continue observing the central limits for one year, but the offer did not lead to a binding agreement. Adding to the complexity is the growing arsenal of China, which was never part of these bilateral US-Russia treaties, raising the prospect of a three-way nuclear competition.

Why these treaties matter 🔗

The arc of these agreements tells a clear story. Early treaties like SALT and the ABM Treaty focused on stabilizing the arms race by setting ceilings and protecting mutual deterrence. The INF Treaty took the bolder step of eliminating an entire weapons category. The START treaties then pursued deep reductions in the core arsenals.

Together, these agreements reduced the combined superpower arsenals from more than 60,000 warheads at the Cold War peak to a small fraction of that figure. They also built something less visible but equally important: a culture of verification, transparency, and dialogue between rivals. Even adversaries who distrusted each other deeply learned to inspect each other’s facilities and exchange detailed data. The erosion of this framework in recent years is a reminder that arms control is not a permanent achievement but an ongoing process requiring constant political will.

What do you think? If mutual vulnerability kept the peace during the Cold War, does the collapse of treaties like New START make the world more dangerous, or were these agreements always destined to be temporary? And with rising powers like China outside the old US-Russia framework, what kind of new arms control architecture could realistically work in a multipolar nuclear world?

References

1. https://history.state.gov/milestones/1969-1976/salt
2. https://www.armscontrol.org/treaties/strategic-arms-limitation-talks
3. https://www.nti.org/education-center/treaties-and-regimes/treaty-limitation-anti-ballistic-missile-systems-abm-treaty/
4. https://www.britannica.com/event/Strategic-Arms-Reduction-Talks
5. https://www.armscontrol.org/factsheets/intermediate-range-nuclear-forces-inf-treaty-glance
6. https://www.nato.int/cps/en/natohq/topics_166100.htm
7. https://www.acq.osd.mil/asda/ssipm/sdc/tc/start1/START1execsum.html
8. https://www.history.com/articles/start-nuclear-treaties
9. https://goodauthority.org/news/good-to-know-as-new-start-expires-whats-next/
10. https://www.state.gov/new-start-treaty
11. https://www.armscontrol.org/factsheets/new-start-glance
12. https://www.icanw.org/new_start_expiration