Wow, the Russians exploded a bomb that was 3000times more powerful than Hiroshima? World War 3 will definetly be the end of man if countrys have bombs that powerful..
Consider that Hiroshima was in the mid to end 1940's, this Soviet bomb was at least 20 years after that. Now consider that its been aproxomatly 40 years since the Soviet bomb, thats double the time it took the to make a bomb 3000 times the size of hiroshima, imagine a bomb 6000 the times of the soviet bomb, thats what we could have now but we wont ever see the explosion of one of those bombs unless it is used in a war because most countries including the united states and the former USSR.
Also in response to the why would you need such a large bomb question, the Soviets spent their resources making bigger bombs whereas the united states used their money to make accurate bombs, basically the soviets were going under the possibility of why guide a bomb to one house you needed destroyed if you could blow up the whole city and be done with it