The following is an excerpt from If It Takes a Thousand Years: From Al-Qaeda to Hamas, How the Jihadists Think & How to Defeat Them.

I entered the cell of the Taliban commander. He had just been captured from the battlefield. I was aghast at the sight of him. Half his face was missing, his skull partially blown away in some battle. His wounds appeared to be old, so I asked him when this happened. “Fighting the Russians,” he said through the translator. Yet there he was, 23 years after the Afghan-Soviet War ended, still fighting the jihad against the infidels.

Most of the Taliban could not read or write, and couldn’t even sign their own name, but in lieu of his signature, I needed his thumbprint on a document for the interrogation, or “interview” as we called it. I reached down to take his hand and press it on the ink pad, only to find out he had no thumb. What would drive someone in such shape to keep fighting us? This is the question I had spent the previous decade searching out answers for leading up to that moment in Afghanistan.

I was serving in the U.S. Army as a Liaison Officer to the Afghan secret police, and facilitated the interrogations of over 400 captured Taliban and Al-Qa’eda members while there. A Taliban leader once told me “You have me in a cage, my fight is over for now, but my children will fight you, and if they don’t win, their children will fight you. If It Takes a Thousand Years, we will win.” Although it didn’t take the Taliban a thousand years to win the battle of Afghanistan, it demonstrates the drive that our jihadist enemies have. They fight generational wars against the West as a whole.

When analyzing our Islamic extremist enemies, it is important for the American people to understand the tribal mindset that so many of our enemies come from. Islam developed from tribal cultures, and many tribal cultures over the past 1,400 years developed under Islam. The Islamic world itself is divided into what I would describe as tribes; you have the Sunni tribe, the Shia tribe, and within that are thousands of other tribes, one of the most recent being the “Palestinian” tribe which has become somewhat of a self-appointed identity by various lost members of other tribes. But in Afghanistan, tribalism is at a level that is virtually unparalleled in the world.