Russia and the United States hold roughly 90% of the planet’s nuclear warheads. A first strike between them is the one exchange the postwar order was built to prevent — because it cannot stay contained. The moment a warhead crosses the pole, NATO’s Article 5 turns a bilateral strike into a coalition war.
Seven or more nuclear powers fire. Strategic arsenals empty into each other’s cities and the resulting soot triggers a nuclear winter — global agriculture collapses and famine threatens over a billion people. This is a civilization-ending outcome, not a survivable war.
Each run starts the same way — Russia launches a first strike on United States — and then the escalation engine plays the alliance cascade forward, decision by decision. Because retaliation, alliance loyalty and doctrine are probabilistic, the 500 runs don’t all end the same way:
Estimated human cost: 14.2 million+ in direct strikes, with billions more at risk from the ensuing nuclear winter.
Modeling note: these pages show the engine’s projected escalation, assuming launched weapons reach their targets. The live 3D simulation additionally rolls probabilistic missile-defense interception, so an individual run there may be less severe. Casualty figures are first-order estimates from capital-population and arsenal data — a floor, not a ceiling.
What each side brings to the exchange, from the simulator’s arsenal data (SIPRI/FAS-derived estimates):
| Metric | Russia | United States |
|---|---|---|
| Nuclear warheads | 6,200 | 5,500 |
| Avg. warhead yield | 500 kt | 335 kt |
| Delivery legs (triad) | 4 | 4 |
| Automated "Dead Hand" | Yes | Yes |
| Population | 144.0 million | 331.0 million |
A strike is never just between two countries. These are the nations the model most reliably pulls into the Russia–United States war (share of runs in which each is drawn in):