You also have to think about the US intel intercept. Was this genuine or was it a set-up by the FSB as part of the wider plan, further enhancing the story that an Islamic terror group was involved.That sort of attack - people doing it genuinely but without knowing who their masters are - is the only way it could be done, but setting that up requires a lot of time and at least as many people in a network as an actual terrorist cell would. The arms would have to be sourced, the attackers recruited, trained, moved about, housed, fed and so on - all with the risk of someone noticing.
It is an awful lot to have to accept when one could just look at the history of these sorts of attacks within Russia, recent information released from the Russian government themselves (never mind the US warning from a couple of weeks ago) and think that a similar group did this.
He absolutely could use this as an excuse to mobilize further mind, even if its just pointing to the public links between Ukraine and Ingushetia independence movements as implying Ukrainian support for this attack.
Also another thing that caught my attention was that the gunmen were all wearing combat fatigues. Why would you do that? in all other mass shootings by Islamist groups the perps were all dressed in civvies so as to blend in. Doesn’t seem to make any sense.