What should the U.S. do about North Korea now?

The U.S. and North Korea continue to exchange threats: Donald Trump warned he could unleash “fire and fury” on Pyongyang; in response, the DPRK warned it would “turn the US mainland into the theater of a nuclear war” and attack Guam.

Meanwhile, Secretary of State Rex Tillerson played down the threats, saying “Americans should sleep well at night.”

What do you think the U.S. should do about North Korea?