Japanese border disputes with China and Russia are thwarting the goals of Prime Minister Naoto Kan's ruling party to improve ties with its neighbors and reduce dependence on the U.S. security umbrella. The disputes have sent Kan's popularity plunging while he struggles to boost an economy. China and Japan are likely to gradually mend fences, given the importance of trade ties and the fact that greater tensions with Japan would increase U.S.-Chinese friction, said Robert Dujarric, director of the Institute of Contemporary Asian Studies at Temple University, Japan Campus.