North Korea's Secret Weapon? Economic Growth.

With the United Nations imposing yet another round of sanctions on North Korea for its nuclear provocations, it's worth asking why such penalties have been failing for more than a decade. One reason is that the North Korean economy is improving more than is commonly understood -- and that will make altering its behavior through trade barriers significantly harder.

The current approach to sanctions is partly based on the assumption that North Korea's economy is a socialist nightmare, but that's no longer really true. Although the country is still poor, its gross domestic product grew by an estimated 3.9 percent in 2016, to about $28.5 billion, the fastest pace in 17 years. Wages have risen quickly, and per-capita GDP is now on par with Rwanda, an African economic exemplar.