There is a cover story for this in Russian media as per their standard practice - the suggestion is that having officials with kids studying abroad undermines the powerful/united Russia idea pushed by government. That makes sense except for the immediate part of this recall. Why do it NOW and not in a few months?

The obvious thing is to protect children of officials who may be in harms way, but honestly that's not enough push people for an immediate recall. Consider how they might be a threat to Russia in a conflict...

My theory: Officials with children abroad in aggressor states could be subject to blackmail and subterfuge. USA swoops up the children of some key ministry official and says "do this or we hurt your kids." That official is now a liability for the Russian government. This is thus a very measured response to the immediate expectation/possibility of foreign conflict and they are ensuring that their own people are not vulnerable via their offshore children.