From early 2013, Obama Administration officials have used a talking point arguing that sanctions will “sharpen the choice” between economic growth and nuclear weapons. And indeed, after each round of nuclear or missile tests, UN sanctions follow, making life a little more difficult for North Korea’s economic actors. However, for the last several years, Pyongyang has regularly signaled that it will not negotiate away its weapons: They are off the table. And Pyongyang still conducts periodic tests.

Why do things this way? This is a surprisingly difficult question, especially given how few precedents there are. In order