North Korea has threatened to annul the 1953 Armistice Agreement that ended the Korean War if the United States and South Korea do not cease joint military exercises by March 11. Pyongyang issued this threat as Washington and Beijing agreed on the language to be used for new U.N. sanctions against North Korea in response to its most recent nuclear test. North Korea makes frequent threats, but even so, the buildup of rhetoric warning that the nearly 60-year-old armistice is fraying — and blaming what it calls hostile U.S. policies — is notable. If North Korea stops respecting the 1953 agreement, it would in essence be declaring that the Demilitarized Zone separating the two Koreas is no longer in effect and the war against the United States is once again active. There are plenty of reasons to believe the threat is merely rhetorical.