The United States is expecting Tokyo to cooperate and assist in tackling its current crisis in the wake of last week's terrorist attacks in New York and Washington, and Japan may not be able to maintain its good relations with the U.S. if it fails to act quickly, according to an American specialist on Japan.

Ezra Vogel speaks in Tokyo about the impact of the terrorist attacks in the United States.

"Of course, everybody now feels sympathy. But countries that are very quick and are ready to cooperate with the U.S. against terrorism will be friends, and countries that don't cooperate or assist won't have the same relationship with the U.S.," Ezra Vogel, a research professor at Harvard University, said in Tokyo.