Well, it's not about agreeing to disagree. As long as NK doesn't use a nuke on another country, I'm right. If they do I'm wrong.

Guys right now it's not a matter of of NK could hit the US. They definitely can hit South Korea and Japan, two US allies that could suffer mass casualties just by being caught in the cross fire. The citizens of those countries are at risk.

Besides China needs NK as a buffer be tween countries allied with the US. They won't sit back and let them topple.

People seems to think that simply having better weaponry makes winning a war easy. Afghanistan and Iraq were supposed to be easy too. NK is way better armed, has a large army and people ready to die if the Supreme Leader says so. It's not like they have a good shot at defeating a US invasion, but this war would be costly and long. And it can only happen if China gets tired of Jon-un's stubborness and decides to abandom them to their own luck. This is quite hard since China won't want to "help" South Korea and Japan by doing so, it will happen only if NK commits a imbecile act of aggression against the US.

Even for the US, this situation could be catastrophic. If NK, with quite a bit of luck, managed to hit a US navy cruiser with a nuclear bomb, the US would face the dillema they always intended to avoid: nuclear counter-attack or not? Would they use nuclear weaponry so close of China and SK? Would it be considered a war crime since civilians would be attacked? But in the case they didn't used nukes and simply attacked NK with massive brute force and conventional weaponry, enough to basically destroy the place, it could send a message to other superpowers that you are allowed to strike the US with nuclear weaponry and they won't counter immediatily. They don't want Russia and China to think that the US wouldn't respond with nuclear force quickly, so maybe a full strike could be feasible.

Realistically, the US will wait for China to get fed up with NK or for them to attack first (so China won't back them up). Then they will try to make Jon-un look like a fool and maybe start up a small revolution with CIA. When the government falls, SK will just unify with NK. The US would probably give them loads of cash so they can fix the famine/economic issues in the North. China would be pissed, but they are probably seeing that NK is becoming more of problem than an asset.

Of course, they absolutely have beaten Vietnam, Iraq and Afghanistan in a few days with ease. NK is way harder to attack and any movement would be seen as a direct aggression to China. They can't afford to fight China, nor China can afford to fight them.

The USA does have some very strong allies in the Pacific which does give them an edge over China in that Regard, especially with Australia and Singapore... Who consequently gave the USA a big strategic edge during WW2. - The USA can leverage Australia's location for supplys, rather than rely on vulnerable Pacific supply lines.

It's a numbers game. And China has the Numbers. Although Japan and South Korea do have the technology and the alliances.

Fighting a modern war involves more than battling on land. The US currently has 12 aircraft carriers in servive and one in reserve with another one currently under construction. By comparison, China has only 1 in service with another under construction. China might have more soldiers, but the US would have more air superiority. Also, if the US managed to destroy that one aircraft carrier, China's airforce will not be going very far from East Asia. 

They didn't make it up, but hopefully they wouldn't be stupid enough to use it. We were at least smart enough to drop nukes when none else had them, and it still haunted the President until he died.

Something I hope to see in my lifetime is the inevitable fall of NK.

On one hand, I want the North Korean government to fall, however on the other hand I don't want them being replaced by other regimes that are going to repress them. I don't have too much confidence in that.

Depends on what happens. Either China will take control over NK after the fall of it, or the US/SK will. If China takes it, I think it'll be a bit better than now. It may still be a dictatorship or perhaps China will absorb it, which I could see since that'd give China more water area, which China wants. If the US takes it, they'll probably hand it over to SK and slowly integrate it back into a single Korea. Those are what I see happening at least. In either scenario, the country is better off.