I sucked at Geography, but even I know where Chechnya is. *facepalm*
If it comes out the brothers did this for Muslim reasons, then I would suspect they were coerced into saying that. Ultimately, if I went off what that guy's article said about the brothers, I'd say it's more likely they were trying to get better jobs and got rejected, so they bombed the Marathon. Or they just did it for shits and giggles; they thought it'd be a blast. Hell, I used to make explosives when I was in high school. I knew a couple guys in college that did it. My chem professor's assistant worked on formulas to make meth during lab. Some people just take things too far (I limited myself to fireworks, not bombs, for the record).
Oh well, I don't really even follow the story. Sure there are a bunch of maimed people and a few dead ones, but as far as bombings go that was pretty lame.