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With the full support of a feckless policy elite and an uncritical media establishment, Washington is slipping, if not plunging, into a new cold war with Moscow. Relations, already deeply chilled by fundamental disputes over missile defense, the Middle East and Russia's internal politics, have now been further poisoned by two conflicts reminiscent of tit-for-tat policy-making during the previous Cold War. In December, Congress, in a fit of sanctimonious lawmaking and indifference to larger consequences, passed the Magnitsky Act. In effect a blacklist without due process, it will punish Russian officials (and perhaps their family members) alleged to be guilty of "gross violations of human rights" in their own country. However odious such individuals may be, Russia's political class was...