To quote a great man, "Another thing that's been in the news lately was that China, which we call "Red China", exploded a nuclear bomb, which we called "a device"."
Well, if you've been awake this past day, it may have come to your attention that a certain insular autocratic regime in Northeast Asia happened to have tested the detonation of a device. And not only a device, but rather a device of nuclear nature, no less. It's funny, they've invented nuclear weapons there but have not yet discovered freedom and the American way. I blame Confucius.
Strictly speaking, this changes nothing, but of course it does. Everyone already knew that North Korea had nuclear capability, it was hardly a secret, but it's a little hard to ignore said nuclear capability when the DPRK whips out its nukes to show to everyone on the playground. Not only does it have them, they work and the government has enough of them to waste one on fucking with the security council. Or South Korea. Or Japan. Whomever. The point is, China and Russia can no longer softpedal the North Korea issue, because it's become clear that North Korea is less than willing to do their bidding. The DPRK went to China shortly before the test to tell them, China said not to do it, and they did it. On the upside, this definitely sets the stage for some feel-good-togetherness-internationalist problem-solving, and maybe the US and China will take a break from pissing at each other over Iran & Sudan to act in concert on something. We could all learn some important life lessons like it's an after-school special. Nothing like righteous outrage for that.
I can't imagine it's the same in the ROK, where I'd imagine they're probably really fucking pissed. Yes, the trick to moderating the North is engagement, trade, and gradual normalization. And the "sunshine policy", how can something that sounds that good possibly be wrong? Apparently, um, they just got made fools of. And instead of their engagement policies making them look nice and sane and friendly, they just got made to look like a bitch. I don't know anything about Korean politics, but I'd imagine that this might set the stage for some serious political shuffling.
Back in Japan, well...Abe is starting off his career with a bang. This being high-grade "Scary Shit" aside, this might actually be good. Unsurprisingly, a lot of Abe's recent visit to China had to do with North Korea and their mutual conviction that a nuclear-armed DPRK is a Bad Thing. I don't know how much the status quo re:North Korea will change, but if it doesn't, this provides for some serious bonding time between the Japanese and Chinese governments. As of the moment that nuke went off, I'm willing to bet that Article 9 is now a dead letter (and who can blame them in the circumstances?). Thing is, it was going to get amended (or repealed) anyway, and this provides the perfect pretext to do so without threatening China. Granted, it'll up tensions in the future, but the act of changing it will be far better understood and handled by the Chinese government. It seems not so far a stretch to imagine the Japanese and Chinese governments working in concert on the issue.
This is exactly the opportunity to do what people are always urging, get China to "invest in the international system". While a war with North Korea would obviously be a Bad Thing (mostly for the South Koreans, who would take the brunt of it), one of the few good things it would do would be greatly strengthen the international order in East Asia. Anything that puts China and Japan on the same side of an argument is, in my mind, a Good Thing, at least in that regard. Any conflict that has them fighting on the same side? Well, that's a Very Good Thing, it makes it much harder to imagine a Sino-Japanese War. By focusing the attention of East Asia on this, it very well might help Abe mend the fences he promised to. Which is great, because he couldn't have otherwise.