When I first met Tamerlan Tsarnaev, now familiar as the elder of the two alleged Boston Marathon bombers, he gripped my hand like he was wringing out a rag. It was 2004, and Tamerlan had been in the U.S. for about a year, but he already had an outsize American dream. He planned to box for the U.S. Olympic Team one day, and he wanted to earn a degree, perhaps at Harvard or MIT, and to hold a full-time job at the same time, so he could buy a house and a car. I suggested he forget the house and the car during college, as most American students do. He didn't see why he should.

I...