Keeping in mind that many Al Quaida operatives received training by "fighting" in Chechnya... IF this was terrorism, and is claimed by the Chechnyan Terror groups, that does not necesssarily rule out an AQ connection.
Just a thought.
If indeed there is a second plane (which the Russian government has apparently acknowledged), to believe this is some sort of coincidental accident is drifting into "magic bullet" territory.
Al Qaeda is with the Chechens.
Alot of Al Qaeda terrorists fought alongside the Chechens and alot of Chechens are fighting alongside Al Qaeda.