Washington (CNN) -- Watching the worst terrorist attack in the nation's history on a TV at CIA headquarters was like a punch in the stomach for Gary Schroen.
The 35-year veteran of the CIA had just entered the agency's retirement program when planes struck the Twin Towers in New York and the Pentagon on September 11, 2001.
Schroen's career had been spent mostly overseas as a covert officer in the Middle East and Southwest Asia. Now in his late 60s, he felt he was going to miss what could be the agency's biggest battle in a land he knew well.
Two days later he was at the forefront, summoned back to duty to lead the first U.S. team into Afghanistan. His mission: Hook up with the opposition Northern Alliance, help beat back the Taliban army and, as he was instructed by his CIA boss, "Find [Osama] bin Laden, kill him and bring his head back to the United States in a box on dry ice".
Schroen said it was clear "the gloves were off, that this was a war, and we were going to get the guys who did this terrible deed".
The original end game seemed pretty straightforward -- destroy al Qaeda and eliminate the Taliban.
But nine years later, current and former intelligence officials tell CNN a battle targeted primarily in one region has spread to a worldwide fight with no end in sight.
CNN
