The reason for his detention was not immediately clear. The situation is made more difficult by the fact that Iran and the U.S. have not had formal diplomatic relations since the hostage crisis of 1979.
Rezaian, 38, has been the Washington Post's Tehran correspondent since 2012. Before that, he frequently traveled between the United States and Iran, working as a freelance writer for several magazines and newspapers, including the Chronicle.
Between 2005 and 2007, Rezaian wrote a blog for The Chronicle called "Inside Iran," which discussed the political and cultural affairs of the largely isolated nation. (Photo credit: Mike Kepka, Chronicle)