ok so

When the invasion launches i will first of all send troops to the north of finland so that the troops will focus on the north and leave completely from the capital which is all the way south.

After that, when the finnish army finally comes to the north, tanks will march fro the middle sourounding the troops.

After killing the troops i would launch a nuclear into the capital slowing down finlands armys.

And After of the finnish armys loss and the nuclear strike the warplanes with the remaining troops and tanks will get the hole country without worries.