Ten Things to Know About Nuclear Weapons
The world remains just one false alarm, a single person's impulsive decision, and a few minutes from nuclear conflagration and an ensuing nuclear winter. Thousands of nuclear weapons around the world are on hair-trigger alert. Once the button is pushed, the order can't be rescinded, and once launched, the missiles cannot be shot down. Despite many historically documented nuclear "near misses," and a renewed rise in global tensions, nuclear risk mitigation receives little attention from policymakers, researchers, and students alike.
Though the number of nuclear weapons has gone down significantly since the 1980s, the current global stock is still high and rising: as of March 2024, nuclear-armed states possessed a combined total of about 12,100 nuclear weapons. Roughly 3,804 of those are operational, and of those, 2,000 are on "high-alert status" — meaning they stand ready to be launched at any time.
The rise of artificial intelligence and modernization of arsenals present the potential for new kinds of accidents and false alarms as unfamiliar technologies are deployed. While states are not seriously considering giving AI models direct control of nuclear weapons, militaries are actively looking to incorporate the technology into a wide array of applications, including military decision-making and early warning sensors — introducing new failure modes into an already fragile system.
The University of Chicago's connection to this risk area runs deep: the world's first controlled nuclear chain reaction took place under Stagg Field in 1942, and the Bulletin of the Atomic Scientists — creator of the Doomsday Clock — was founded in 1945 by Manhattan Project scientists at UChicago concerned about the technology they had helped create.
Some experts believe the world is at its highest level of nuclear risk since the Cuban Missile Crisis. With Russia's war in Ukraine, China's rapid nuclear modernization, and heightened tensions in the Middle East, the chance of escalation — deliberate or inadvertent — is dangerously high. Here are 10 things to know:
~3,800 operational nuclear weapons exist today, with 2,000 on high-alert status.
As of March 2024, nuclear-armed states possessed a combined total of about 12,100 nuclear weapons. Roughly 3,804 are operational, and of those, 2,000 stand ready to be launched at any time.
Nine states possess nuclear weapons.
The United States, Russia, China, the United Kingdom, France, India, Pakistan, North Korea, and Israel make up the "Nuclear Nine." Nearly all maintain a policy of nuclear retaliation in self-defense; only two have vowed "no first use." The U.S. and Russia hold more than 90% of the global stockpile.
Nuclear winter remains the worst consequence of nuclear weapons use.
Firestorms from detonations over cities could loft soot high into the atmosphere, blocking sunlight and dropping global temperatures by 20–40°F — causing crop failure, famine, and infrastructure collapse. Even an exchange as small as 100 warheads could starve more than 2 billion people.
Very few people are required to authorize a launch.
Despite differing command structures across the nine nuclear powers, launch authority typically rests with a head of state. In the U.S., France, and North Korea, that authority is held solely by one person.
The world has come dangerously close to nuclear war before.
In 1983, Soviet officer Stanislav Petrov disregarded a false satellite warning of incoming U.S. missiles, preventing a retaliatory launch. The Cuban Missile Crisis and the 1983 Able Archer exercise are two more documented "near misses."
China’s rise is disrupting Cold War-era bipolar stability.
With the U.S., China, and Russia now possessing comparably large arsenals, the "three-body problem" makes deterrence calculus and negotiation harder than the bipolar U.S.–USSR dynamic of the Cold War.
Key arms control treaties are expiring, with few replacements in sight.
Treaties including SALT, the CTBT, New START, the JCPOA, and the CFE Treaty have expired or been withdrawn from in recent years, weakening the frameworks — like the NPT — that remain.
Nuclear and conventional weapons systems are increasingly entangled.
The deployment of "dual-use" weapons and shared command, control, and communications infrastructure makes it harder for adversaries to distinguish conventional from nuclear threats — raising the risk that a conventional attack escalates into a nuclear one.
Funding for nuclear risk research is drying up.
Philanthropy invests only about $40–50 million per year globally in mitigating nuclear risk — a number expected to fall further after the MacArthur Foundation, once roughly 30% of the field’s funding, exited in 2024. Governments, by contrast, spent $91.3 billion on nuclear weapons in 2023.
AI is being integrated into nuclear-adjacent military systems.
While states are not seriously considering giving AI direct control of nuclear weapons, militaries are incorporating it into decision-making and early-warning sensors — introducing new failure modes, from automated escalation to false alarms, in an already fragile system.
What XLab is doing about it
Our nuclear risk research program works on resilience, risk reduction alternatives, and the field’s foundational inputs.
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