Lol @ repairing the railroad on the fly in hostile territory. They bring enough supplies to do that every couple miles?
That train stops to fix one oops, they'll find another behind them and 20 more in front.
Of course with modern weapons, they could blow that train off the track from 100 miles away while it's traveling 70mph.
As for treaties, Russia has demonstrated that nothing they sign is worth the paper it's printed on. Only a chump would pretend otherwise.
If they're not going to honor their treaty about the sovereignty of Ukrainian, why should NATO worry about one for Kaliningrad.
Lithuania is at peace. I don't see how it will benefit from destroying their own railways. They are testing the Russians and watching their reaction.