The final legal pillar of global nuclear arms control, the New START (Strategic Arms Reduction Treaty), officially expired today. After 15 years of regulating the world’s two largest nuclear arsenals, the lapse of this treaty marks the beginning of an unregulated and uncertain era of atomic competition.

United Nations Secretary-General António Guterres described the expiration as a “perilous moment for the world,” expressing deep concern over the collapse of the decades-long arms control architecture.

In a formal statement, Secretary-General Guterres remarked, "As of midnight, the world has entered a reality where the two major nuclear powers are no longer bound by international legal constraints on their strategic weapons. For the first time in over half a century, we face the risk of an unmonitored and unbridled nuclear arms race."

He further added, "This divorce comes at a time of peak geopolitical tension. In an environment without transparency, a single miscalculation or technical error could lead to a global catastrophe."

Signed in 2010 in Prague by then-President Barack Obama and Russian President Dmitry Medvedev, the treaty became the cornerstone of international security. Its primary objectives included:
Restricting both nations to a maximum of 1,550 deployed strategic nuclear warheads. Allowing each nation to conduct up to 18 on-site inspections per year to verify compliance. Mandating the exchange of data regarding the location and movement of missiles and bombers.

While the treaty was extended for five years in 2021, the geopolitical landscape shifted drastically following the conflict in Ukraine. Russia formally suspended its participation last year, citing "hostile" Western policies, while the United States maintained that it could no longer provide unilateral transparency. Without a replacement or a new framework, the legal limits on the world's deadliest weapons have now vanished.