Source of Disaffection

For John, BLUF:  Unhappy youth.  Nothing to see here; just move along.

From someone who is a bit of an expert in these things:

These guys likely had no connection to the Caucasus Emirate in person; connection would likely have been online.

This looks more and more like "resonant effects,"♠ rather than something planned and executed by a cadre-level organization.

Chechens I know are completely crushed.

That is to say, two unhappy youths, not part of some larger Islamic extremist group with terror as a method.  Not part of some focused Chechen effort to obtain independence from Russia.

Not likely there are other like cells here in this area or across the US.

Regards  —  Cliff

♠  Resonance—Physics the reinforcement or prolongation of sound by reflection from a surface or by the synchronous vibration of a neighboring object.  That is to say they picked this up from the back and forth of the Internet.