A 2004 NBC report graphically illustrated what not having this program cost us 4 1/2 years ago. In 1999, the NSA began monitoring a known al Qaeda "switchboard" in Yemen that relayed calls from Osama bin Laden to operatives all over world. The surveillance picked up the phone number of a "Khalid" in the United States--but the NSA didn't intercept those calls, fearing it would be accused of "domestic spying."

After 9/11, investigators learned that "Khalid" was Khalid al-Mihdhar, then living in San Diego under his own name--one of the hijackers who flew American Airlines Flight 77 into the Pentagon. He made more than a dozen calls to the Yemen house, where his brother-in-law lived.

NBC news called this "one of the missed clues that could have saved 3,000 lives."