Three years later, the Army's chief of staff concedes the United States is up against a highly adaptive "thinking" enemy.

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Paul said he did not dispute that the president has the authority to take swift and lethal action against an enemy that carried out a significant attack against the United States.

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Fortunately for him, several years later a shift in clan enmities and alliances ended the whole cycle of revenge killings and united both clans against a common enemy, a neighboring tribe.

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