The prefix neo- refers to two ways in which neoconservatism was new. First, many of the movement's founders, originally liberals, Democrats or from socialist backgrounds, were new to conservatism. Also, neoconservatism was a comparatively recent strain of conservative socio-political thought. It derived from a variety of intellectual roots in the decades following World War II, including literary criticism and the social sciences.
Irving Kristol, Norman Podhoretz and others described themselves as neoconservatives during the Cold War. In general, however, the movement's critics use the term more often than supporters. In fact, some people described as "neocons" today say that neoconservatism no longer exists as an identifiable movement.
Many associate neoconservatism with periodicals such as Commentary and The Weekly Standard, along with the foreign policy initiatives of think tanks such as the American Enterprise Institute (AEI) and the Project for the New American Century (PNAC). Neoconservative journalists, pundits, policy analysts, and politicians, often dubbed "neocons" by supporters and critics alike, have been credited with (or blamed for) their influence on U.S. foreign policy, especially under the administrations of Ronald Reagan and George W. Bush.
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http://en.wikipedia.org/wiki/Neoconservativism