Yes, Web, you have to ask did they do a cost benefit analysis? Is it going to cost more than what they will gain? I mean the resources they would expend in the initial offensive would be tremendous, and do they have the men?
Couple that with can they hold their new positions in what would most certainly be a hostile region with a counter attack comming in the near future, so could they even hold any gains they would make?
And then the scenario was similiar to the reason the mexican forces invaded the US SW presumably to protect its nationals, whereas Canada does it to prevent American refugees from overwhelming them.
Why? Its colder up there thus it would take more.
So why would anyone even consider going up north? Besides, going North is like going "uphill." Going South is easier as you are going "downhill"