The Tsar Bomba was tested during a time of Cold War tension, when the United States was developing its ICBM missile systems and engaging in the Operation Dominic nuclear tests on the Pacific islands. The USSR needed to demonstrate its might, and originally planned a 100 megaton nuclear test. It was scaled back to 50 megatons to minimize fallout because it was calculated that winds would blow the dust cloud across northern Russia. The effects were astonishing. Tsar Bomba was a huge bomb, about the size of a car. The USSR's heaviest carrier plane had to be modified in order to carry it. The bomb was outfitted with a special slow parachute, to give the plane time to travel a substantial distance away before the bomb was detonated. When the bomb exploded, the fireball was so tall that it touched the part of the sky where the plane was upon release. The mushroom cloud it produced was 60 km (37 mi) tall, almost seven times higher than Mount Everest, and 30-40 km wide.