The 2025 decision of the Bulletin of the Atomic Scientists to move the Doomsday Clock to 89 seconds to midnight was the closest to symbolic catastrophe in its 78-year history. It is not a prediction but a warning: a distillation of global threats from nuclear weapons to climate change and disruptive technologies. As the 2026 update approaches, the underlying conditions that shape its setting have revealed an increasingly dire landscape of nuclear danger and the erosion of safeguards.
At the heart of these current issues is the fact that the New START treaty reaches expiration on February 5, 2026. It has imposed verifiable limits on U.S.-Russian deployed strategic nuclear forces for over ten years. If it is not renewed or replaced, this would be a first in decades where the two largest atomic arsenals would be free to expand without constraint. Erasing transparency, both sides would have to rely on worst-case assumptions a dynamic long linked with arms races the stripping away of on-site inspections, data exchanges, and notification regimes would occur.
This is compounded by the rapid build-up of China’s nuclear forces. The Pentagon believes Beijing’s stockpile-in the low 600s in 2024-is apt to surpass 1,000 warheads by 2030. Satellite and intelligence reports suggest more than 100 solid-fuel intercontinental ballistic missiles have been loaded into newly built silo fields. The Chinese modernization program includes mobile and silo-based missiles, intermediate-range systems and possible low-yield warheads, as well as new plutonium production capacity. China is not a party to any strategic arms limitation treaty like that binding the U.S. and Russia.
These developments occur against a backdrop of growing geopolitical tension. North Korea is continuing to improve its nuclear capabilities, India and Pakistan are perfecting their delivery systems, and U.S. allies such as South Korea, Japan, and Saudi Arabia have expressed interest in nuclear options in the case of growing regional threats. To many, U.S. extended deterrence-a cornerstone of nonproliferation policy-is being stretched across multiple theaters, with discussions about further deployments and new delivery systems such as the proposed nuclear-armed sea-launched cruise missile. Technological change is adding new layers of complexity. Major powers are incorporating artificial intelligence into military systems, including elements of nuclear command, control, and communications.
A recent United Nations resolution expressed concern over AI-driven decision compression, misinterpretation, and decreased human oversight. While a few states stress the potential of AI to augment early warning and resilience, most judge that it will undermine crisis stability even when human officials retain formal launch authority. Meanwhile, the forty-year moratorium on U.S. nuclear explosive testing is under political assault. Declarations by U.S. leadership at the end of 2025 provided an opening to resume underground tests “on an equal basis” with other powers. The technical need for such tests is widely disputed by weapons scientists, but a return to testing by any nuclear-armed state would erode the fragile norm created by the Comprehensive Test Ban Treaty, risking reciprocal tests by Russia, China, and others.
Treaty erosion, arsenal expansion, emerging technologies, and shifting alliance dynamics-the conjunction of these factors underlines why the Doomsday Clock stands so close to midnight. Any one factor would support concern; intertwined, these create a web of risk more difficult to handle than the bilateral nuclear standoff that defined the Cold War. The symbolic time the Bulletin’s Science and Security Board will choose-as it considers its 2026 decision-reflects not just the state of arms control, but the collective burden of accelerating these threats.
