The top U.S. trade official says Japan still has a long way to go before it can say its markets are open, according to AP. U.S. Trade Representative Michael Froman told reporters on Friday that the Japanese market remains closed off in important ways and he is mindful of the historical difficulties in opening it up. Still Froman said he hopes Japan's recent entry into the Trans-Pacific Partnership free trade negotiations will provide opportunities to tear down barriers to U.S. and other foreign imports. In particular, Froman mentioned autos - one of the thorniest issues in U.S.-Japan trade relations. Froman said all foreign penetration of the Japanese auto market is now only 6 percent. He spoke ahead of a trip to Japan and Brunei that will revolve around the trade deal negotiations.