There are agreements that end with speeches, and others that simply expire, like light fading from a long afternoon. The last major nuclear arms control pact between the United States and Russia passed into history this way—without ceremony, without signatures, and without a sense of arrival. Its end was marked only by the turning of a calendar page.

For decades, these treaties had acted as quiet architecture beneath global security. Born from the anxieties of the Cold War, they were designed to impose ceilings on arsenals capable of erasing cities, to slow the pace of rivalry by turning suspicion into measurement and verification. Inspections, data exchanges, and mutual limits formed a language of restraint, spoken even when relations elsewhere fell silent.

The most recent agreement, New START, capped deployed strategic nuclear warheads and delivery systems, offering a final thread of continuity between Washington and Moscow. Its expiration now leaves no binding limits on the world’s two largest nuclear stockpiles for the first time since the early 1970s. The moment is less explosive than symbolic—a thinning of rules rather than a sudden rush to rearm—but symbols have a way of shaping behavior.

This ending arrives amid strained diplomacy and hardened rhetoric, with both nations modernizing their nuclear forces and questioning the value of inherited frameworks. Efforts to negotiate a successor treaty stalled as trust eroded, inspections were paused, and dialogue narrowed. What once required painstaking negotiation now struggles to find a table at all.

Beyond the numbers and clauses lies a subtler loss: the habit of talking. Arms control was never only about warheads; it was about predictability, about knowing roughly where the other stood. As that habit fades, uncertainty expands, filling the space where limits once stood.

The expiration does not mandate escalation, nor does it guarantee collapse. But it closes a chapter written over half a century, when rivals accepted that even hostility required boundaries. The world now watches a quieter, more ambiguous horizon, where restraint must be imagined anew—or risk being forgotten altogether.

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Sources Reuters Associated Press Council on Foreign Relations Brookings Institution Arms Control Association