Tsar Bomba (AN602)

In the mid-1950s, the United States had an unconditional superiority over the USSR in nuclear weapons, although thermonuclear charges had already been created in the USSR at this time. (WIKIPEDIA)

also called Big Ivan, a Soviet thermonuclear bomb that was detonated in a test over Novaya Zemlya island in the Arctic Ocean on October 30, 1961. The largest nuclear weapon ever set off, it produced the most powerful human-made explosion ever recorded. (Britannica)