It's a tricky process getting polar bears back into the US. There are quite a few papers to go over, it does cost some money. The government/border patrol will give you a time frame which you have to have the bear back by. If not, then you have to re-do the paperwork. You have to arrange appointments with border patrol for when you cross so they can examine everything. There is quite a bit of work that goes into getting a bear back, but it can be done.