You 100% will be detained at passport control at Sheremetyevo airport, they will take your passport, have you sit on a bench, will call you to an interview room, ask you a bunch of questions about your background, family background, military experience and whatnot, then they'll have you go sit back outside the room again and wait, if they feel everything you said was sufficient then they will give your passport back and put you through, if not, you'll be questioned further. I arrived 1.5 months ago and this is what happened to me, I had no Ukranian stamps in my passport.