Rather than trying to keep pace with America's increasingly precise guided missile delivery systems, Russia's solution was to build and test a bomb that was so big that aim literally didn't matter. It was like losing an archery competition and throwing a hand grenade at the target to remind the winner just how little aim mattered in the face of your sheer ass-slapping lunacy.
The Tzar Bomba was so impractically big that creating a parachute to slow its descent disrupted the Soviet textile industry. If you're wondering why they needed a parachute in the first place, it's because no matter how high you dropped it from, the resulting explosion would reach up into the sky and disintegrate your plane unless you gave yourself some kind of head start. In fact, the bomb was originally supposed to be twice as big as it ended up being, but they realized that it would be impossible to drop such a bomb from an airplane without killing everyone aboard. Also, it probably would have cracked the earth like an egg. Who the hell knows?
"If we don't try to destroy all life on earth, we'll never know if we can."
The scaled-down version of the bomb was still big enough to cause a fireball that was seen 600 miles away, meaning if it was dropped over Manhattan, you would have been able to watch New York City burn from Virginia. Windowpanes would have been broken down through South Carolina. Even though they dropped Tsar Bomba over a deserted area in the Arctic Circle, wooden houses were destroyed and stone houses had their roofs blown off hundreds of miles away. The shock wave was so extreme that even with the parachute giving them a 20-mile head start, the plane that dropped it was knocked into a free fall for a half-mile before catching itself and continuing to get out of Dodge.