People were/are worried about fusion bombs for the same reasons they were/are worried about fission bombs, except more so because the yield of a fusion bomb is typically much higher than the yield of a fission bomb. So a fusion bomb typically does more of everything a fission bomb does.
Yes, America does possess hydrogen bombs
Because it is highly explosive
Atomic bombs, not hydrogen..The U.S. in August 1945.
The main difference between atomic bombs and hydrogen bombs is the source of their energy. Atomic bombs rely on nuclear fission (splitting atoms), while hydrogen bombs use a two-stage process involving both fission and fusion (combining atoms). Hydrogen bombs are more powerful and destructive than atomic bombs.
Of course, hydrogen bombs are real from more than 60 years.
Radioactive fallout
No.
There were no hydrogen bombs (fusion bombs) detonated during WWII.
They never used hydrogen bombs in Japan. They used nuclear bombs which produces gamma rays not the lethal doses of x-rays produced by the hydrogen bomb.
Hydrogen bombs have never been used in war. They have only been exploded in test shots.
Of course not, it was just for fun (by the way the bombs at Hiroshima and Nagasaki were uranium bombs and not hydrogen)
Hydrogen bombs use the same process of nuclear fusionthat powers the Sun.