Let's think of it this way. The USA are the terrorists really simply because they invaded some random country in the 70s, 80s or 90s without thinking about the future. These countries should not have been invaded as they had no right to, it is like Nazi Germany's invasion of Poland. They want to exterminate communism, so they declared war on many god damn communist countries. Yet when they are 'invaded' by terrorists, they call them 'terrorists' when they did the exact same many years or decades prior. If the US don't like what they are getting then why dish it out in the first place? They are only going to make the situation worse by giving the so called 'terrorists' (as described in the media) attention. All they want is to kill and to get attention.
Listen little boy, what your saying is that it's ok for the US to have nuclear weapons because they are responsible with them but if any other country has them we should nuke them because they might nuke us for no apparent reason. I'm sorry, what?
If any country was to launch a nuclear warhead at America then they would ultimately not care about their country being nuked as well because by the time that first nuke is launched, America will have every single one of their's going straight towards that country. That means that both country's would have been fucked and nobody wins or proves anything.
The whole world would be in danger if this were to happen. The one nuke wouldn't just affect the countries firing at each other but the whole world, which is why I believe the UN are trying to get rid of nuclear weapons. Getting rid of them is a fair initiative but as Gerard said, it's impossible.