It's order of magnitudes easier to stop Iran from getting the bomb rather than "disarming" them completely.
And there are good reasons for countries having at least some kind of army. You need a police force to stop a few gangsters from teaming up and raiding weaker civilians. You need an army to prevent/deter the police forces of your neighbor countries to team up and overwhelm your police force to take your stuff.
"My imaginary friend is better than yours!!"