“Easier world, are you kidding?” say conservatives. “Reagan was up against a Communist superpower that had thousands of nuclear missiles aimed at us! How can you say that?”

Here’s how: The defining struggle in Reagan’s day was the Cold War, and the defining feature of the Cold War was that it was a war between two different systems of order: Communism versus democratic capitalism. But both systems competed to build order — to reinforce weak states around the world with military and economic aid and win their support in the Cold War. And when either Moscow or Washington telephoned another state around the world, there was almost always someone to answer the phone. They even ensured that their proxy wars — like Vietnam and Afghanistan — were relatively contained.

Obama’s world is different. It is increasingly divided by regions of order and regions of disorder, where there is no one to answer the phone, and the main competition is not between two organized superpowers but between a superpower and many superempowered angry men. On 9/11, we were attacked, and badly hurt, by a person: Osama bin Laden, and his superempowered gang. When superempowered angry men have more open space within which to operate, and more powerful weapons and communication tools, just one needle in a haystack can hurt us.