John Roos (left), U.S. ambassador to Japan, shakes hands with Japanese Prime Minister Naoto Kan before their talks at Mr. Kan's office in Tokyo on Tuesday, June 22, 2010. On Monday, Mr. Kan said he will reassure President Obama when they meet at a summit this weekend that Japan-U.S. ties continue to be "the cornerstone" of Japan's diplomacy. (AP Photo/Yoshikazu Tsuno, Pool)

Photo by: Yoshikazu Tsuno

John Roos (left), U.S. ambassador to Japan, shakes hands with Japanese Prime Minister Naoto Kan before their talks at Mr. Kan's office in Tokyo on Tuesday, June 22, 2010. On Monday, Mr. Kan said he will reassure President Obama when they meet at a summit this weekend that Japan-U.S. ties continue to be "the cornerstone" of Japan's diplomacy. (AP Photo/Yoshikazu Tsuno, Pool)