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Gen. Stanley McChrystal this week expressed a truth that military commanders know better than anyone: "A political solution to all conflicts is the inevitable outcome," he told the Financial Times. The problem is getting to that political settlement in a way that the combatants find acceptable. This can take years, even decades.

The United States is now in its ninth year of fighting Muslim extremists around the world. People sometimes wonder whether America has learned anything during this painful time, or whether we are condemned to keep digging deeper holes for ourselves. Certainly, we're still digging in Afghanistan, where McChrystal, the U.S. commander there, believes that an acceptable political settlement won't be possible unless we squeeze the Taliban harder. I think he's...