Cultivating multiple enemies simultaneously is unwise.Playing Russian Roulette with multiple bullets in the barrel. How many are there ?

We have North Korea,  Iran, Syria. Others too would probably like to take a crack at us like who(m)? So if they all "COLLUDE" and join together to take us out think they'd win? How many nuclear weapons can we deploy at once? Thousands, hundreds, dozens, one?  How many can a consortium of our enemies deploy at once directly at us? :(