Feb 27, 2014 — The U.S. and South Korea are conducting joint military exercises. In the past, the North has used missile tests to express its displeasure. On Thursday, South Korean officials say, it did so again.
Mar 15, 2013 — North Korea has been increasingly hostile, warning of a preemptive nuclear strike on the U.S.
Mar 11, 2013 — Experts worry that while the North has often made threats, now it's rhetoric is ratcheting up. That may make the new young leader, Kim Jong Un, feel as if he has to follow through on the threats in some way.