TOKYO—New U.S. Defense Secretary Lloyd Austin, during his first phone call with his Japanese counterpart, reaffirmed America’s commitment to Tokyo to defending a group of East China Sea islets claimed by both Japan and China, the Pentagon said. Austin, in talks with Japanese Defense Minister Nobuo Kishi, confirmed that Article 5 of the U.S.-Japan security treaty, which stipulates U.S. defense obligations to Japan, covers the uninhabited islands, the Pentagon said in a statement. The islets are known as the Senkaku islands in Japan and Diaoyu in China. Austin also reaffirmed that the United States remains opposed to any unilateral attempts to change the status quo in the East China Sea, the Pentagon said. Japan has become increasingly concerned about Chinese activity in the East China Sea, including incursions into waters around the islands. The talks marked the first ministerial discussions between Tokyo and Washington since U.S. President Joe Biden took …