We've never had to confront a really nationalistic American government since the War of 1812. But if it ever happened, it would be trouble for us. Such a government would be prepared to use trade as a club in dealing with us - one of many, if it decided to take American power out for a walk around the block. I don't mean military occupation or anything like that, but a desire for unquestioning adherence to whatever the nostrum of the day happened to be. That's rather scary. We've never had to deal with an American president who was completely a wing-nut.