While an individual nuclear weapon may be controllable in isolation, even a relatively controlled nuclear strike may prompt other countries to respond with counter-strikes that themselves violate international law. Many countries, including the United States, take the position that under the doctrine of causation, the decisions of the other country to counter-strike constitute an intervening cause that breaks the chain of causation, absolving them of responsibility for the effects of the subsequent strikes. This blog post examines exceptions to the doctrine of intervening cause that would potentially hold the country behind the initial strike responsible for the effects of the subsequent counter-strikes. Given the risk of escalatory counter-strikes in the context of nuclear weapons, these exceptions raise questions about the durability of the legality of nuclear weapons.