Japan and the United States marked the 50th anniversary of the signing of the San Francisco Peace Treaty and their postwar alliance Saturday, with Foreign Minister Makiko Tanaka expressing contrition for Japan's wartime deeds and Secretary of State Colin Powell assuring Tokyo the alliance will remain strong.

The treaty formally ended the state of war between Japan and the Allied powers, and cemented Japan's postwar ties with the U.S.

In a ceremony Saturday morning to commemorate the 50th anniversary of the Japan-U.S. security pact, Tanaka and Powell addressed the geopolitical significance of the trans-Pacific alliance, calling it the linchpin of peace and prosperity for the Asia-Pacific region.

"While the Asia-Pacific region has experienced several conflicts and crises over the past half century, today peace prevails in the region. The security arrangement between Japan and the United States is the anchor for this peace," Tanaka told a gathering at the Presidio, the now defunct U.S. military post where the security pact was signed.