On 6 August 1945, a US Air Force bomber dropped a bomb known as “LIttle Boy” on the Japanese city of Hiroshima and destroyed it. This week, states party to the Nuclear Non-Proliferation Treaty (NPT) started a 4-week meeting in New York to review the Treaty, 52 years after it entered into force. The NPT is both an arms control and a disarmament treaty. Today, arms control is weak, disarmament seems far off, war rages in Ukraine and crisis builds over Taiwan. It is time to remember just how destructive Little Boy was. Retrospectively, it is clear the first nuclear weapon used in war was well-named for what happened to Hiroshima is the least of what we can expect if a nuclear war were to start today.