HONOLULU -- Japan-U.S. relations are at a postwar high, "the best they have ever been," report policymakers on both sides of the Pacific and longtime observers of the relationship. Credit growing realism in Japan about security issues, unprecedented decisions in Tokyo and a remarkable personal relationship between the leaders of the two countries. But Japan's current activism is unsustainable. The country has neither the interest nor the resources to continue on its current trajectory.

Both governments need to prepare for that eventual readjustment: Washington must alter its expectations of Japan, and Tokyo needs to articulate more clearly its view of the relationship and how it will share burdens with the United States. Failure on either side could plunge the relationship to lows that mirror the gains of recent months.

Japan-U.S. relations have been transformed since the 9/11 terrorist attacks. Much of the credit goes to Prime Minister Junichiro Koizumi. He has overseen the historic dispatch of Self-Defense Forces to assist the international coalition in the war against terror, has been a staunch supporter of the U.S. in its attempt to rally world opinion against Iraq, and earlier this month secured passage of historic legislation that gives the government expanded powers in times of national emergency.