I hate to quibble, but it was Snowden that exposed the American spying on Merkel. 

The bigger quibble is with the assertion that Obama did it. Given the number of people working for American intelligence agencies, there is no possible way the president can keep track of everything they are doing. I do not remember any report that said that Obama authorized, or was even aware of, the bugging of Merkel's cell phone; just that it happened during his administration.