Richard M. Nixon has long been the Freddy Krueger of American political life. You know in your bones that he is destined to keep returning. Sure enough, though dead 16 years, Nixon is back onstage, with the release of a fresh batch of tapes from his Oval Office days. They show him at his omni-bigoted worst, offering one slur after another against the Irish, Italians and blacks. Characteristically, he saved his most potent acid for Jews. “The Jews,” he said, “are just a very aggressive and abrasive and obnoxious personality.”But Nixon’s hard-wired anti-Semitism is an old story. What has caused many heads to swivel is a recording of Henry A. Kissinger, his national security adviser. Mr. Kissinger is heard telling Nixon in 1973 that helping Soviet Jews emigrate and thus escape oppression by a totalitarian regime — a huge issue at the time — was “not an objective of American foreign policy.”“And if they put Jews into gas chambers in the Soviet Union,” he added, “it is not an American concern. Maybe a humanitarian concern.”In New York, the epicenter of Jewish life in the United States, some jaws are still not back in place after dropping to the floor.