Sen. Bernie Sanders is calling National Security Agency electronic surveillance of some of America's closest allies "outrageous."
Sanders wrote to President Barack Obama to express his views after reports that the NSA spied on heads of state in Brazil, Mexico, France and Germany.
Sanders pointed to reports that the U.S. hacked into the cellphone of German Chancellor Angela Merkel and had harvested more than 70 million French phone records.
Sanders says he worries that such activities will harm the ability of the U.S. to gain its allies' full cooperation in combating international terrorism.