North Korea will not "attack". They will do an extra-atmostpheric nuclear test, like many such tests done in the past by the US and USSR. At a high altitude, li

North Korea will not "attack". They will do an extra-atmostpheric nuclear test, like many such tests done in the past by the US and USSR. At a high altitude, like about 400km. There will be no fall-out, no loss of life, no damages. But they will score huge point, despite the fact that their nuclear capability is far from being end-to-end. What they are missing right now is mainly the reentry vehicle, but aside from that solid-fuel rockets and submarines capable of launching SLBM's. At the pace they are advancing, the re-entry vehicle is probably within their reach in two years or so. But if they are suffocated by the sanctions, they won't be able to carry out their rocketry R&D. So it's vital for her to do the extra-atmospheric nuclear test, that is their only existential hope. On the other hand, it's also very important for China for this not to happen. Once this happen, the US can justifiably start investing in earnest in the ABM defense, and there are several options that can be pursued: beefing up the current options, like the ground-based midcourse defense, the Aegis and the THAAD systems, but also more experimental ones, like laser based defense, or rail-gun based. China has a nuclear doctrine that is strictly deterrence based (i.e. no firs strike, including no pre-emptive strike). In the face of a much more effective US ABM defense, their deterrence can disappear and that means they either change their doctrine, or engage in an arms race which they see no good reason to do. So it's almost as important for China not to let NK to do their extra-atmospheric test. However, my money is that NK will do that test in the next 6 months.