The National Security Agency was able to continue spying on Americans' emails long after the government said it had shut down the metadata program in December 2011, according to a new NSA inspector general report obtained by the New York Times. By shifting operations overseas, the NSA created a functionally equivalent program and continued analyzing social links revealed by Americans' email habits, but with even less oversight.

Prior to November 2010, NSA spies were barred from analyzing Americans' data that had been collected abroad, but that rule was changed, making the NSA's existing collection program in the U.S. redundant. The report said the domestic program was then shut down in part because "other authorities can satisfy foreign intelligence requirements." The other three reasons for shutting the program down were redacted from the report, which was obtained by the Times through a Freedom of Information Act request.

The shift allowed the NSA to collect the same amount of metadata outside of U.S. borders — often times regarding communications between two American citizens — and do so without having to worry about constitutional protections or oversight from the Foreign Intelligence Surveillance Court, according to the Times.

"The document makes it clear that NSA is able to get all the Internet metadata it needs through foreign collection," Timothy Edgar, a privacy official in the Office of the Director of National Intelligence under Presidents Barack Obama and George W. Bush, told the Times.

"The change it made to its procedures in 2010 allowed it to exploit metadata involving Americans. Once that change was made, it was no longer worth the effort to collect Internet metadata inside the United States."

The NSA likely relied in part on authorities provided under the Special Procedures Governing Communications Metadata Analysis guideline, which allows the agency to use metadata to create social networks of Americans for any "foreign intelligence" purpose, according to the Electronic Frontier Foundation.

The report said the NSA wasn't actually able to read the text of emails, but could intercept and analyze certain types of Americans' data while the information was shifted between servers in different countries, according to Engadget.