Key Point: The Tsar Bomb convinced its creator to become an anti-nuclear activist.
On July 10, 1961 Soviet Premier Nikita Khrushchev summoned the USSR's top nuclear weaponeers and told them to promptly resume nuclear testing. After roughing up America's young new President Kennedy at a Vienna summit in June, Khrushchev was in a mood, according to Andrei Sakharov, to “show the imperialists what we can do.”
For two years while their country joined the United States and the United Kingdom in a voluntary moratorium on nuclear tests, Soviet nuclear scientists, including Andrei Sakharov, the “father of the Soviet hydrogen bomb,” developed and refined new weapon concepts and designs. Now they had to deliver big results in very short order. Khrushchev wanted a political spectacle to shock and awe the West, and it had better go right.
The Communist Party's 22nd Congress in October 1961 required something special. It isn't clear who proposed a 100-megaton bomb—Khrushchev or the weaponeers—but at the premier's command the most powerful nuclear weapon ever built had to be ready in only four months.
Such a huge bomb came about only because Soviet scientists had a good idea about how to proceed. As Carey Sublette of the Nuclear Weapons Archive website explains, “It is safe to assume that the 100 Mt bomb was a very conservative design - one that pushed no technical envelopes save for size. The two principal reasons for thinking this are the extremely compressed development schedule, and the very high profile of the test.”
High-profile indeed. Khrushchev's next move came on August 13, 1961, when East Germany began erecting the Berlin Wall. On August 31 the Premier announced the giant new bomb and the abrupt end to the USSR's voluntary moratorium; a Soviet atmospheric nuclear test followed the day after. The US responded in kind within the month.
With the Cold War escalating no time was spared. Andrei Sakharov's team at Arzamas-16, the "USSR's Los Alamos," skipped the careful mathematical analysis require for H-bomb design and worked out "Big Ivan" on the fly using approximations. At the time the largest device the Soviets had tested yielded much lower, so to achieve 100 megatons Sakharov's team used clustering and staging.