Hoo boy, this one's going to be difficult to explain. A new document leaked to Der Spiegel by former NSA contractor Edward Snowden indicates the NSA had taps on German chancellor Angela Merkel's phone for over a decade. 

The German newspaper reports the NSA had Merkel's cell phone number listed on a Special Collection Service (SCS) document since 2002. The number was listed as recently as June 2013 -- the last time President Obama visited the country. The document also alleges the U.S. has a "not legally registered spying branch" in the U.S. Embassy, one that would lead to "grave damage for the relations of theUnited States to another government," if exposed, according to a Reuters translation. U.S. are or were able to wiretap German government communications without letting them know they're being spied on. So how have Merkel and the White House responded to this report so far? 

Both sides refused to comment, according to the Guardian

Merkel was already miffed about previous reports indicating the National Security Agency was monitoring her phone. The White House promised, very carefully, that it's not monitoring Merkel's phone right now. White House spokesman Jay Carney dodged accusations the U.S. picked up Merkel's phone number along with 35 other world leaders leader earlier this week, saying the U.S. "is not monitoring and will not monitor" her communications. Given his unsatisfactory response, never denying spying on her phone calls in the past, Merkel arranged a meeting between German and U.S. officials this week to discuss the NSA's alleged surveillance. This latest report won't help warm that already chilly relationship. 

It's unclear how much and what kind of data the NSA collected on Merkel. There's no indication whether the spying agency listened to her phone calls or just logged the call meta data, as is their most common practice. That's Obama's best chance to save face with the German leader.