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Understandably, Mexican President Felipe Calderon is trumpeting the navy's success in taking down Arturo Beltran Leyva, wanted in the United States and Mexico for his part in the $15-billion to $20-billion-a-year drug trade. He was a criminal known to behead his rivals and believed to be responsible for last year's killing of the federal police chief in his Mexico City home; he was the most powerful cartel boss to be removed by security forces since Calderon launched his drug war in 2006. The operation reportedly was the result of improved U.S.-Mexican intelligence cooperation, and although the naval troops failed to take Beltran Leyva and six cohorts alive, it should yield a trove of new information. Moreover, the battle between cartel grenades and the navy's mounted machine guns was...