During the first year of the Carter administration the United States has sometimes "given an impression of indirection and inconsistency" in its policy toward Japan and East Asia, Ambassador to Japan Mike Mansfield said yesterday.

"The problem, I am convinced, is one of perception rather than of reality," Mansfield told an audience at the Japan Society.

Mansfield attributed the misunderstandings between Washington and Tokyo in large part to the transition in U.S. policy that followed the end of the Vietnam war and the advent of new governments almost simultaneously in Washington and Tokyo.

While blaming the United States for muddying the waters by not making clear enough Washington's commitment to East Asia, Mansfield also said that the Japanese have been "slow to recognize that their economic power imposes responsibilities."

The former Senate majority leader cited three major problems that arose in bilateral U.S.-Japanese relations during the first year in Tokyo: economic issues, President Carter's plan to withdraw U.S. troops from Korea and the Carter decision to forgo nuclear reprocessing with the possibility that Washington would compel Tokyo to follow step.

He praised the compromises that were worked out on nuclear reprocessing and on trade issues and urged that Americans realize that Japan's economic concessions entail "genuine sacrifice, painful adjustment in wide sectors of its economy, and significant political risk."

Mansfield said that Japanese fears caused by the plan for U.S. troop withdrawal from Korea have been eased, but that Americans should realize "we have the vital responsibility to maintain a strong and credible military force in East Asia."