A new study by the Japanese Automobile Manufacturers Association has found 70 percent of Japanese vehicles sold in the U.S. were built on a North American assembly line.According to TheDetroitBureau.com, the study found that more than 400,000 jobs have been created by Japanese automakers since Honda opened its first facility in the U.S. in 1982. Honda Toyota and Nissan had a total of 29 plants operating in the U.S. in 2010 with a combined investment of $34 billion. Those numbers are likely to increase in the coming years.The Japanese Three have made no secret that the companies are looking to guard their operations against an ever-stronger yen. Odds are we'll see even more Japanese facilities open their doors in Mexico, the U.S. and Canada Toyota is slated to open a new line in Tupelo, Mississippi, and Honda is expected to begin assembling the Fit in Mexico soon.But Toyota, Honda and Nissan aren't just building vehicles in the U.S. for American consumers. Japanese-owned plants here are also producing vehicles for consumption abroad. Last year, a total of 145,000 vehicles were built in the U.S. for foreign markets by Japanese automakers, up from 95,000 units in 2010.