Former CIA director and retired Gen. David Petraeus during his address Tuesday at the University of Southern California. Frederic J. Brown /AFP/Getty Images hide caption

itoggle caption Frederic J. Brown /AFP/Getty Images

Then-Army Gen. David Petraeus (left) and Marine Corps Gen. John Allen in August, 2011. Chip Somodevilla/Getty Images hide caption

itoggle caption Chip Somodevilla/Getty Images

Then-Gen. David Petraeus in mid-2011, just before he became CIA director. Barbara Sax/AFP/Getty Images hide caption

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David Petraeus, while he was the top commander of U.S. and coalition forces in Afghanistan, and Paula Broadwell in July 2011. He resigned from his post as CIA director because of an extramarital affair they had. ISAF/Reuters /Landov hide caption

itoggle caption ISAF/Reuters /Landov