Do you remember where you saw this? Even if it were true, I'd be skeptical that this will affect Japan automaker plans much vis-a-vis US production. Whatever the rules in place, they can always be changed. Reagan pushed through voluntary export restraints, and he was the most free-market president we've had since Silent Cal. Besides, costs in Japan are prohibitive. Labor is about the same, but land, utilities and sundry items are prohibitively expensive. Shipping costs are a factor, since cars take up a lot of space and are pretty heavy.
Here:
http://www.ustr.gov/about-us/press-office/fact-sheets/2013/april/US-consultations-Japan
As with so many things done by the US Government, the frosting on top sounds really nice.
It’s only when you drill down into it you find you’re eating whipped cream spread over a turd.