because we could
1952
that we knew how to build one
The hydrogen bomb.
It increased the nations fear of one another
Yes, both.
atomic bomb or the hydrogen bomb
A long time
1945
To defend against a possible Nazi atomic bomb!
1945
The H-Bomb, or Hydrogen Bomb, has never been used in warfare- the bombs dropped on japan at the end of WW2 were ATOMIC bombs, which are not as destructive. The Hydrogen Bomb is very much more powerful than the atom bomb, and has only ever been exploded in tests. For full information, Google 'US Hydrogen Bomb' and see what comes up.
The US tested a nondeliverable prototype device in 1952The USSR tested a deliverable but limited bomb in 1953 (this would not be considered a hydrogen bomb now, instead a boosted fission bomb)The US tested a deliverable bomb in 1954The USSR tested a deliverable bomb in 1955