Japan is an "underachiever" that needs to play a larger international role commensurate with its resources and capacity, the head of an influential U.S. think tank told a recent symposium in Tokyo.

A more internationally active Japan is essential given that the world today is a mixed bag of historically rare opportunities coupled with new sets of daunting challenges, to which there can be no unilateral solutions, said Richard Haass, the president of the Council on Foreign Relations.

While the United States needs to "rebalance its approach to the world" and reorient its foreign policy, Tokyo and Washington must rethink the roles of their bilateral alliance so that they can jointly meet the challenges of the new era, said Haass, who served as a special assistant to U.S. President George Bush between 1989 and 1993.