Appearing on CBS News Sunday, former CIA agent Hank Crumpton revealed that the U.S. had a chance to kill terrorist mastermind Osama bin Laden months before the attacks of Sept. 11, 2001, but the Clinton administration didn't take the shot.

While using an unmanned aerial drone to spy on members of al Qaeda in 1999, Crumpton said he watched as bin Laden himself stepped out of a vehicle convoy. Understanding that he'd been ordered to kill bin Laden on sight, Crumpton got the White House on the line immediately.

But that's where it got sticky, he explained.

"The Clinton administration’s response was, 'Well, it will take several hours for the TLAMs, the cruise missiles launched from submarines, to reach that objective. So you need to tell us where Bin Laden will be five or six hours from now,'" Crumpton said. "The frustration was enormous."

The missed opportunity was a key turning point in the CIA's approach to drone aircraft, he explained. "[Arming them] was a response to the lack of response on the part of the administration or [Department of Defense]," Crumpton said.

The first Predator drone to be weaponized with Hellfire missiles was tested in February 2001, according to George Washington University's International Affairs Review. The Obama administration has used drone aircraft to bomb more targets than his predecessor, President George W. Bush, and his top advisers feel that using drones is more humane than sending soldiers into a remote part of the world to needlessly risk their lives.

Bin Laden would go on to help facilitate the attacks of Sept. 11, 2001 and evade capture until last year, when he was shot several times by Navy SEALs during a raid on his compound in Pakistan. Crumpton said that a drone never got another clear look at him, despite their increasing prevalence.

His killing has since become something of a political football in the U.S. presidential election, with President Barack Obama touting his decision to send troops in for a capture-or-kill operation that resulted in bin Laden's death. He's also released an advertisement featuring President Bill Clinton praising Obama's decisiveness -- something Obama's challenger, presumptive Republican nominee Mitt Romney, has objected to.

This video is from CBS News's 60 Minutes, broadcast Sunday, May 13, 2012.