From: Virginia, USA
I have yet to see a loss against the NKVD reg at the Rum border by a PzDiv. However, one div will not secure the south end of the pocket. Your need two -- the NKVD, as well as the mot/arm units nearby and the strong inf div to the east have a lot of ability to break encirclements. Also the mot div up to the NE.
There is a way to do it with one division, though it is not sure fire and that is why I recommend attaching the MG battalion:
Obviously, I haven't tried to break that position, but it looks pretty dicey for the Krauts. The INF DIV to the east should be able to move one hex directly west. Then the rest of the guys to the west can move east (hitting a Rum Cav to clear the way).
My understanding of the isolation rules is that once the pocket is broken, all the ISO penalties go away (other than some movement and attack capabilities based on supply). IOW, if you make a big pocket that breaks, you wasted your time, and might have well just concentrated on cutting rail lines.
Well, I have tried to break it and it can't be done. There is no way for the Russians to reach the hex just north of the cavalry units which will convert to German control during the logistics phase. And no one has either the movement points or the strength to take out those cavalry units.