How many times have you heard the question asked of U.S. policymakers: does this mean you could use nuclear weapons and the answer: we are keeping our options open; nothing is off the table?
So, if you were constantly being threatened with annihilation by someone with the means to do that unless you complied with their desires/orders, would you not seek to have those same means? Of course you would. No one likes to be kicked about by a bully much less being forced to grovel before that same bully for your very survival.
While war criminals like Bush and Cheney continue to walk free, no nation will ever believe that they are not under threat of annihilation by U.S. nuclear weapons. Until the U.S. government no longer threatens others with nuclear weapons on behalf of those who seek profit, others will seek the means to strike back with equal ferocity. Understanding that is the first step toward understanding others.