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The president and his national security team have outlined an ambitious strategy for Afghanistan. But if they hope to meet their July 2011 target date for the beginning of a U.S. drawdown, they will have to navigate some unavoidable roadblocks along the way.

The first -- and most pressing -- is the continued weakness of the government of Afghan President Hamid Karzai. Some commentators have written that the withdrawal of presidential candidate Abdullah Abdullah from the second round of elections this past fall has cleared the way for Karzai -- with U.S. support and aid -- to begin necessary reforms. Richard Miniter and Sebastian...