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Saudi Arabia is leading a coalition force into Bahrain to help the government calm the unrest there. This move puts Iran in a difficult position, as Tehran had hoped to use the uprising in Bahrain to promote instability in the Persian Gulf region. Iran could refrain from acting and lose an opportunity to destabilize the region, or it could choose from several other options that do not seem particularly effective.

The Bahrain uprising consists of two parts, as all revolutions do. The first is genuine...