DEARBORN, Mich. -- Friction with the United States may be triggered by Japan's increasing trade surplus in the near future, the head of Ford Motor Co. warned July 17.

Speaking to Japanese reporters, Alex Trotman, president and CEO of Ford, expressed concern about Japan's recently rising trade surplus and said the trade relationship between the two countries must be more balanced. "The increasing trade surplus of Japan with the United States is going to cause trade friction again," he said. "I think that has to be reversed."

The yen's decline against the dollar is believed to be a major factor that led to the expanded trade surplus, and increased Japanese automobile exports are often blamed for that fluctuation. Commenting that the yen's current level against the dollar is too weak, Trotman said an adequate exchange rate would be somewhere between 100 yen and 110 yen for both Ford and the U.S. automobile industry as a whole. He also said Ford will engage in more joint projects with Hiroshima-based Mazda Motor Co. in the coming years, especially in Asia.