My guess is that their nuclear program is a failure. While this collapse may not be the absolute cause, I'm assuming they've had much bigger related issues, and

My guess is that their nuclear program is a failure. While this collapse may not be the absolute cause, I'm assuming they've had much bigger related issues, and are no longer able to sustain their threats. Combine that with the number of sanctions on them, they really have no choice. https://www.cnn.com/2018/04/26/asia/north-korea-nuclear-test-site-punggye-ri-intl/index.html https://www.cnn.com/2018/04/26/asia/north-korea-nuclear-test...