I suspect a good bit of it was from us taxpayers via federal, state, and local govt. A full menu of Baraqqi benefits that so many partake of these days.
If these were two welfare “yutes” from Cambridge it might be more believable that they acted alone, but it’s impossible to dismiss their background and activities. How likely is it that yahoo #1 travels to chechnya for 6 months, and then he comes back and unleashes this sneak al qaeda style attack without reference to the known terrorist he was seen meeting with on his trip? Hard to believe all this was just a wild coincidence.