A document leaked to The Guardian by Edward Snowden suggests that German chancellor Angela Merkel wasn't the only world leader whose phone was tapped by the NSA. Nearly three dozen leaders might have been tapped after asking American officials for the information in their contact lists.

The paper reports on an October 2006 memo that outlines how the NSA acquired the private contact data:

"In one recent case," the memo notes, "a US official provided NSA with 200 phone numbers to 35 world leaders … Despite the fact that the majority is probably available via open source, the PCs [intelligence production centers] have noted 43 previously unknown phone numbers. These numbers plus several others have been tasked."

The memo was intended to encourage more such contact-list-sharing, despite the agency acknowledging that tracking the numbers yielded "little reportable intelligence." The success of finding those 43 unknown numbers, though, "leads S2 [signals intelligence] to wonder if there are NSA liaisons whose supported customers may be willing to share their 'Rolodexes' or phone lists with NSA as potential sources of intelligence," The Guardian quotes the document as saying. "S2 welcomes such information!"

The timing for this revelation is particularly tricky given tensions between Germany and the United States over reports that Merkel's phone was one of those included in the NSA's snooping. As Reuters reported on Wednesday, it received a tip from a German official that a document published by Der Spiegel included Merkel's phone number. At his daily press briefing, White House spokesman Jay Carney was evasive, according to Reuters, saying President Obama assured Merkel that the U.S. "is not monitoring and will not monitor" her communications.

He continued, "As the president has said, the United States is reviewing the way that we gather intelligence to ensure that we properly balance the security concerns of our citizens and allies with the privacy concerns that all people share."

That language — not now, not in the future — leaves open the question of past behavior. To Reuters, a White House source declined to say if Merkel's communications had ever been monitored. Carney echoed that on Thursday. This morning, the German foreign minister demanded the U.S. Ambassador meet him to discuss the issue.

Last month, The New York Times reported that the NSA actively built out social network systems from known information. We also knew that the agency made connections up to three relationships away from existing targets: if the NSA was watching you, they could also be watching your friends' friends' friends. The new report from The Guardian suggests that in 2006, the NSA didn't have to go that far. If you knew certain members of the U.S. government, the NSA was tracing your communications.

Photo: President Bush and Merkel in 2008. (AP)