In case you missed the follow-on reporting yesterday: USA never paid $2 million to North Korea over Otto Warmbier. I still think it was bad to sign a promise to pay the money to get Warmbier back before he died. But the fact that it wasn't paid matters. https://www.cnn.com/2019/04/25/politics/otto-warmbier-north-korea-comatose-bill/index.html …
That's why it was done, but international negotiations are about much bigger stakes. Entering a high-stakes nuclear negotiation, you don't blink over the very first effort to extort you.