Han Solo said in rec.pets.dogs.behavior:

I encourage
this behavior
by showering her with praise when she returns, and that
seems to be working at
least. Huskies are inherently escape artists, I read --
perhaps there's nothing
short of physical barriers that will work to contain her.

You might find that once you stop her from going over, she'll
find a way to go under or through. The only way to safely
contain her might be to close up the dog door.

--
--Matt. Rocky's a Dog.