All of this raises the question of whether China is acting in good faith. By cooperating, China might gain economic concessions from the United States, but it’s unclear how long they would last. And China might actually welcome a United States obsessed with a North Korean ICBM aimed at the U.S., since this might divert U.S. focus in East Asia from China to North Korea permanently. Finally, while common sense would suggest that China has significant leverage with North Korea, that should not be overstated.

Economically, North Korea is relatively self-sufficient. It has chosen poverty over dependence. The economic sanctions China can impose, such as blocking North Korean coal exports, have already been used in previous crises. The North Koreans, moreover, haven’t trusted China since the Korean War, when China made no attempt to intervene until the U.S. threatened to cross the Yalu River into China. Absent that, the Chinese, having encouraged North Korea to invade the South, were willing to see North Korea fall. Using China as a negotiator might seem logical, but China has few chips to play and a history of betrayal.

Mattis presented this issue in an interesting way in Singapore. On the one hand, he expressed confidence in China on North Korea. On the other hand, he ripped into Chinese policies in the South China Sea as violating international law. The message was that nothing China does in North Korea will make the U.S. concede the South China Sea, which was a relief to the audience in Singapore. But Mattis also conveyed the message to China and others that the U.S. is not confident in finding a diplomatic solution to this crisis.

Eoin Treacy's view

North Korea achieving the technological and physical capabilities to develop an intercontinental ballistic missile represents a significant issue for the US military. That’s because unlike “the line in the sand” that use of chemical weapons in Syria represented, this would have direct geopolitical implications for the continental USA. 

As we move into the summer months, the time for a short campaign before the North Asian winter sets in is approaching its optimum timing while at the same time many stock markets are somewhat overextended relative to their respective trend means. That suggests an escalation of tensions with North Korea could potentially represent a catalyst for a reversionary move.