As the world ponders the fate of Egypt after Hosni Mubarak, Americans should ponder this: It’s quite possible that if Mubarak had not ruled Egypt as a dictator for the last 30 years, the World Trade Center would still be standing.

This is true even though Mubarak’s regime has been a steadfast U.S. ally, a partner in our counterterrorism efforts and a foe of Islamic radicalism. Or, more aptly, it’s true because his regime has been all of these things.

In “The Looming Tower,” his history of Al Qaeda, Lawrence Wright raises the possibility that “America’s tragedy on September 11 was born in the prisons of Egypt.” By visiting imprisonment, torture and exile upon Egypt’s Muslim Brotherhood, Mubarak foreclosed any possibility of an Islamic revolution in his own country. But he also helped radicalize and internationalize his country’s Islamists, pushing men like Ayman Al-Zawahiri  Osama bin Laden’s chief lieutenant, and arguably the real brains behind Al Qaeda  out of Egyptian politics and into the global jihad.

At the same time, Mubarak’s relationship with Washington has offered constant vindication for the jihadi worldview. Under his rule, Egypt received more American dollars than any country besides Israel. For many young Egyptians, restless amid political and economic stagnation, it’s been a short leap from hating their dictator to hating his patrons in the United States. One of the men who made this leap was an architecture student named Mohamed Atta, who was at the cockpit when American Airlines Flight 11 hit the World Trade Center.