The National Security Agency ended a program used to spy on German Chancellor Angela Merkel and a number of other world leaders after an internal Obama administration review started this summer revealed to the White House the existence of the operation, U.S. officials said. Officials said the internal review turned up NSA monitoring of some 35 world leaders, in the U.S. government’s first public acknowledgment that it tapped the phones of world leaders. European leaders have joined international outrage over revelations of U.S. surveillance of Ms. Merkel’s phone and of NSA’s monitoring of telephone call data in France. The White House cut off some monitoring programs after learning of them, including the one tracking Ms. Merkel and some other world leaders, a senior U.S. official said.