BEIJING (AP) — U.S. Defense Secretary Leon Panetta is in China where he may get a frosty reception from officials unhappy with America’s expanded military presence in the Asia-Pacific region.

His three-day visit comes amid escalating tensions over territorial disputes involving China and Japan, and questions about whether the U.S. is backing its Japanese allies in those disagreements.

This is Panetta’s first trip to China as defense chief, and it is expected to include several historic visits, including meetings with the country’s leaders. Panetta’s stay in China was extended in recent days so that he could visit a key naval base where he will see a Chinese submarine and frigate.

According to U.S. defense officials, Panetta plans to press China to seek ways to peacefully resolve regional territorial disputes.