It is now looking like the Boston bombers were part of a terror attack

[Chan790]

12. I doubt Boko Haram had anything to do with the Tsarnaev brothers.

Any more than Al-Shabaab did.

If you were being at-all serious, I would tell you that the most-likely candidate is rogue factions of Vilayat Dagestan (formerly known as Shariat Jamaat), though there are several Georgian and Chechen Islamicist organizations that are/were capable of it, not even getting into Al-Qaeda aligned groups.

The entire disputed region of the Caucasus Emirate is very gas-and-oil-rich. This is of substantially greater interest to the Russians than the US however...it's their energy companies that hold the contracts, their energy workers and allied regimes that the Chechens and Dagostanis want to drive out.

Based however on the respective positions of the combatants and their stated disinterest in US engagement (All Islamicist factions in the C.E oppose action against non-Russian civilians, and particularly American civilians because they don't want US forces or boots on the ground and they view us as an arms-length strategic neutral party due to our own icy relations with Moscow)...it seems most likely that whoever backed, funded and provided material support to the Tsarnaevs was a radicalized rogue faction acting outside the purview of their own leadership...or very very stupid--the best hope they have of victory is US outrage against the genocidal tactics of the Russians and subsequent international pressure. The way to not get it is to bomb American civilians at a sporting event half a world away.