U.S. Secretary of Defense Leon Panetta is visiting China for four days amid an escalating sovereignty dispute between China and Japan over a group of islands in the East China Sea.

The U.S. defense secretary’s trip is a return visit for the Chinese defense minister’s visit to the U.S. early this year.

Panetta will discuss pending issues, such as the sovereignty dispute between China and Japan and the U.S.’s construction of more missile bases in Japan.

On Wednesday, Panetta will meet with Chinese Vice President Xi Jinping, who is expected to succeed current leader Hu Jintao.

In the meeting with Xi, the U.S. defense secretary will likely reiterate that the U.S. will not side with China or Japan in the sovereignty dispute. Panetta will also urge China to take measures to ease the mounting tension between the two neighbors.