Canadian National Debt

I just came across the current Canadian national debt numbers on the StatsCan website. It’s a bit higher than I thought, roughly C$619 billion. According to the chart this is balanced against C$111 billion of assets, but I’m unclear what that actually represents. I’m not sure if I’d consider the net number as actually representative of our real situation. After all, we can’t just pawn Fortress Louisbourg if the US economy tanks.