Reports stated it was a TU-22M3--to us, a Backfire bomber/recce plane. Swingwing, and supersonic capable. That is a huge airplane, almost 2/3rds the size of a B-1B. And notably, it is an Air Force type plane. A carrier plane is stressed to land without flaring at up to a design descent rate. If you are used to looking at carrier landings, then this one doesn't seem too abnormal.
It looked like they suffered a tailstrike. If they did, then it would be more likely that it was mishandling by the crew or a blind approach instrumentation problem that caused the breakup.
One source was reporting it was a 30 year old airframe. The last one off the line would be 22 years old if published records are correct. That kind of detail may--or may not--be true, and may not really be relevant. Depends on the design life and maintenance. It was notoriously bad during the Soviet years. The Russians have been upgrading these recently. The M3 is current, I believe, and they plan to do a bunch of them.
Really lousy weather. Not just heavy fog and low visibility--with all that snow on the ground there would be little to no contrast. I can't imagine attempting this, but professional pilots do. These aircraft have a recent history of overrunning runways. On a snow and ice covered runway, you don't flare and tippy-toe, you plant it and try to keep it from overrunning. Still, it looked like the pilot rotated, but had not arrested the descent at all.