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North Korea's vow to launch a satellite next month has flummoxed some observers. But unless China steps in forcefully, everything will go according to Pyongyang's plan.

Now what? Just when you thought it was safe to go back into the Six-Party Talks, the North Koreans pulled the rug out from under everyone, including themselves, by announcing a planned satellite launch to commemorate Great Leader Kim Il-Sung’s 100th birthday celebrations.

Pyongyang argues that there’s a difference between long-range ballistic missile tests (which it recently foreswore) and satellite launches using a long-range ballistic missile as the launch vehicle; a distinction lost on most others, very specifically including the U.N. Security Council, which has banned...