The advantage was that we could use them to stop WWII. And even that is doubtful, since the Japanese were already suing for peace. Many people today think the real purpose of using the weapons was to scare the USSR. After our victory in Europe the Russians marched into Eastern Europe and took many countries over. We were trying to dissuade them from doing this in Asia as well.But after that there were no advantages. In the 1950s we did experiments with nuclear bombs that showed that the nuclear fallout was MUCH more dangerous than anyone had anticipated. We learned that the radioactive dust kicked up into the atmosphere by large-yield weapons threatens the entire world. We built smaller 'battlefield' nukes but even though we've been engaged in military activities throughout the world every year since WWII, we've never been able to use these small nukes. We've spent trillions of dollars to develop several new generations of nukes, knowing all along that they were basically useless, except as a deterrent.In fact, every nuclear nation (except the US of course) has signed a no-first-use agreement. They know that whoever uses them first loses. No national leader can imagine a scenario by which he has anything to gain by using them, because the whole world will gang up against him after that first use.(It's true that terrorists might use them, people who just want to make trouble, and who have nothing to lose. But it's not as easy for them to get their hands on them as you might think. And every weapon has a radioactive 'signature' that would trace it back to country of origin, and that country would have a lot of explaining to do.)I like the way Carl Sagan put it best--The nuclear arms race is like two people standing in a room, up to their waists in gasoline, arguing over who has more matches.Small countries want nukes today to protect themselves. They serve as a deterrent to attack. For instance, how long do you think North Korea would have lasted without them? They are a tiny, weak country. But with nukes they are at least left alone.