Comment by copsarebastards

Our incentives have changed. At the time, the US was afraid of Japan (and justifiably so). But US military presence in Japan for the last half-century has meant that the Japan doesn't have to invest any money in security: they have instead invested that money in becoming one of the strongest economies in the world. And that has happened, to a large extent, at the expense of US taxpayers. The interdependence of our economies makes the US less afraid of Japan trying to take over the world, and the US economy is no longer strong enough to be propping up the economies of other nations.