START Treaty expiry raises fears of a new global nuclear arms race

Key Concepts

• START Treaty: A series of bilateral treaties between the United States and the Soviet Union (later Russia) limiting strategic nuclear weapons.
• Mutually Assured Destruction (MAD): A doctrine of military strategy in which a full-scale use of nuclear weapons by two opposing sides would result in the complete annihilation of both.
• Anti-Ballistic Missile (ABM) Systems: Systems designed to intercept and destroy incoming ballistic missiles, perceived as destabilizing by Russia.
• Strategic Stability: A condition where the risk of unintended escalation to nuclear war is minimized.
• Escalatory Spiral: A process where actions taken by one party in response to perceived threats from another lead to a cycle of increasing tension and hostility.
• Nuclear Arsenal: The total number of nuclear weapons possessed by a country.

Implications of the START Treaty’s Expiration

Professor Andrew Leam outlines that the immediate implications of the START treaty expiring are “not very much,” but emphasizes the long-term risks. The treaty’s original purpose, stemming from the Cold War, was to maintain “mutually assured destruction” – a stable, albeit terrifying, balance of power where both the US and Russia possessed enough nuclear weapons to survive a first strike and retaliate, ensuring total destruction for both sides. The START treaty aimed to reduce arsenals to 1500 warheads each, fostering “strategic stability.”

However, the context has changed. The development of US anti-ballistic missile systems, initially termed “Star Wars,” eroded Russia’s deterrent capability, as it reduced the certainty of a retaliatory strike. Simultaneously, the US is increasingly concerned about China’s nuclear modernization and expansion, which is not covered by the START agreement. This shift in circumstances creates uncertainty, potentially leading to a trilateral agreement involving China, or, more concerningly, a three-way arms race. Leam notes that “most people would have preferred START to be extended…and expanded to include Beijing.”

The Threat of a Multi-Polar Nuclear Arms Race

The US and Russia collectively hold approximately 90% of the world’s nuclear arsenal. With the treaty’s “guard rails” removed, the primary threat is the expansion of arsenals by both nations, potentially triggering a similar response from other nuclear powers like India and China. This would result in a “three or four-way arms race,” increasing the risk of accidental escalation due to the sheer complexity and number of weapons.

Leam explains, “The more missiles you have, the more things can go wrong, the more insecurity is generated, the more expense is entailed.” He highlights that strategic stability is achievable with lower levels of nuclear weapons, while instability increases with larger arsenals. The expiration of START risks a return to a situation where “anything can go wrong.”

Drivers of Escalation: Insecurity and Cost

Despite the financial burden, an arms race is driven not by rational cost-benefit analysis, but by “insecurity.” The logic is that if one side possesses a significant advantage, the other will feel compelled to increase its arsenal to maintain a credible deterrent. This creates an “escalatory spiral,” where each side responds to the other’s build-up, leading to a continuous cycle of expansion.

Leam illustrates this with an example: “If the other side has 10 nuclear weapons, the other side wants 20, then the other side wants 40, then you can see how that continues.” He acknowledges that both Russia and the US have other priorities – Russia is engaged in a war in Ukraine, and the US has other domestic and foreign policy concerns – but insecurity remains a potent driver of military build-up. The addition of expensive technologies like anti-ballistic missile systems, and the involvement of China and India, further exacerbate the risk of an uncontrolled escalation.

Putin’s Offer and the Erosion of Trust

Last fall, Russian President Vladimir Putin offered to abide by the treaty’s limits informally for another year while negotiations continued. However, the US, under President Trump, did not respond. Leam considers this a “mistake,” arguing that even without a formal treaty, both sides could have continued to adhere to the limits as a gesture of goodwill and to prevent an arms race.

However, the Ukraine war and the US pursuit of anti-ballistic missile systems have eroded trust between the two nations. The inclusion of China further complicates the situation for the US. Leam concludes that, ideally, the treaty could have been continued even after its expiration, but “we don’t live in that world,” and the expiration is likely to have “real real world consequences.”

Conclusion

The expiration of the START treaty represents a significant setback for nuclear arms control. While the immediate impact may be limited, the long-term risks of a multi-polar arms race, driven by insecurity and exacerbated by technological developments, are substantial. The erosion of trust between the US and Russia, coupled with the emergence of China as a major nuclear power, creates a volatile environment where the possibility of accidental escalation is increasing. The failure to respond to Putin’s offer to extend the treaty informally, even temporarily, represents a missed opportunity to maintain a degree of stability in a rapidly changing geopolitical landscape.