You've missed a huge part of geopolitical politics there, Rorty.
There have been terrorist attacks in Russia for more than a decade due to Russia's military involvement in Chechnya - which dates to at least the Soviet era but got particularly nasty from 1994 during the Chechan War, in which there was some very, very bad shit.
This is a territorial conflict; it isn't caused by Islamism. (See also Russia's threats to Finland and the Baltic, and invasion of Ukraine.)
IIUC, it's actually the other way round. The horrendous conflict in a largely Muslim country, ignored by much of the outside world, has driven the Islamist narrative that people should combine and organise internationally as Muslims to protect Muslims.
The rather long-winded point being, that it's not the case that "take out Daesh (ISIS), and everything's fixed". If Daesh do turn out to be involved, it's a manifestation of a pre-existing problem.
And of course it can become circular and self-sustaining which is just lovely for everyone.
Meanwhile, back in St Petersburg... Noofly, I'm so glad your friends are OK. Hope your trip goes safely.