By Stephen C. Webster | Raw Story | Jun. 19, 2012

In a letter (PDF) recently sent to Senators Ron Wyden (D-OR) and Mark Udall (D-CO), the National Security Agency’s (NSA) Inspector General explains that he cannot provide an estimate of how many Americans the agency has spied on, because doing so would “would itself violate the privacy of U.S. persons.”

That letter was first obtained by reporter Spencer Ackerman at Wired. It claims that even attempting to produce an estimate of how many Americans the agency has spied on is “beyond the [Inspector General's] capacity,” and that “dedicating sufficient additional resources would likely impede the NSA’s mission.”

Inspector General I. Charles McCullough concludes his letter by claiming that he “firmly [believes] that oversight of intelligence collection is a proper function of an Inspector General,” adding that he will “continue to work with you and the Committee to identify ways that we can enhance our ability to conduct effective oversight.”

While it’s not surprising that an NSA official would simply refuse to respond to any and all questions from Congress — they typically do — it is unusual for the agency to claim that a basic oversight function like estimating how many Americans have been spied on is effectively too great a task for them to even attempt, and may actually be beyond the purview of the Inspector General.

“All that Senator Udall and I are asking for is a ballpark estimate of how many Americans have been monitored under this law, and it is disappointing that the Inspectors General cannot provide it,” Wyden told Ackerman. “If no one will even estimate how many Americans have had their communications collected under this law then it is all the more important that Congress act to close the ‘back door searches’ loophole, to keep the government from searching for Americans’ phone calls and emails without a warrant.”

A bill passed in 2008, shortly before President George W. Bush left office, gave the NSA broad new powers to spy on electronic communications so long as it believes one participant is outside of the U.S. As a Senator from Illinois, Barack Obama claimed he was opposed to the bill, but ultimately voted in favor of the new powers.

The NSA is legally constrained from tapping Americans’ communications, but numerous whistleblowers have emerged over the last decade, telling reporters with  MSNBC, The New York Times, The Los Angeles Times, and Wired that virtually all electronic communications are being funneled into the agency.