Sunday's overwhelming victory by the Liberal Democratic Party has created a dilemma for the United States, which wants closer economic and military ties with Tokyo even as it fears that Prime Minister Shinzo Abe and his Cabinet now have free reign to pursue a hard-line diplomatic stance that will damage U.S. interests in East Asia.

Concern about Abe in Washington was present well before Sunday's Upper House election. A May report by the Congressional Research Service went so far as to warn that due to tensions between China and Japan over the Senkaku Islands, the U.S. could find itself taking sides in a shooting war, while Abe's views on history, the report said, were not good for the U.S.

"Comments and actions on controversial historical issues by Prime Minister Abe and his Cabinet have raised concern that Tokyo could upset regional relations in ways that hurt U.S. interests. His approach to issues like the so-called 'comfort women' sex slaves from the World War II era, history textbooks, visits to the Yasukuni Shrine that honors Japan's war dead, and statement on a territorial dispute with South Korea will be closely monitored by Japan's neighbors as well as the U.S.," the report said.