Think about it. The Allies had WW II pretty much won, Japan was on the ropes. But the USA used nukes anyway. Now turn it around, if the USA and North Korea get in a war and it looks like North Korea is about to lose, why WOULDNT they use nukes? That fat boy leader of theirs does not care about his people, only about his power. If he is going to go down he is going to take everyone down with him, just like Hitler did. And since everyone things WW III is going to be a nuclear war, then yes, once a nuke goes off we are in WW III. I seriously doubt Trump will let the USA or the US military get nuked without nuking back. The BEST I can see this all turning out is North Korea fires off an ICBM over the Pacific and does an air detonation of a nuke. That will cause an EMP and problems in Hawaii. Trump will tell China and Russia that we will strike back within 48 hours unless they do something. Since they both border NK and both have Military forces on the border, I am willing to bet they will invade NK and take care of the whole problem without the USA having to nuke NK. That will also play into the power book of China and Russia, giving them more land and control over off shore waters.