(CNN) -- Just as President Barack Obama secured his re-election, a scandal jolted his national security team. The resignation of retired four-star general David Petraeus as CIA director over an extramarital affair followed by the investigation of the top U.S. commander in Afghanistan, Gen. John Allen, in relation to e-mail exchanges with a woman caught up in the Petraeus mess is just one of many dramas to unfold following a presidential re-election. Is Petraeus pillow talk a security threat? Here, we take a look at big scandals and controversies that plagued other presidents after voters re-elected them to the White House:
@highlight
Scandal engulfing Petraeus has jolted Obama's national security team
@highlight
George W. Bush hurt by Katrina; Bill Clinton was impeached
@highlight
Reagan was dogged by Iran/Contra, and Watergate ended Nixon's presidency
@placeholder appeared on TV stating there were no "arms for hostages" deal but later admitted that there had been.