By VOAFrom VOA Learning English, this is In The News.American Secretary of Defense Chuck Hagel was in China this week. His visit was an example of efforts by the two countries to expand military ties. The Defense Secretary met with Chinese President Xi Jinping and visited China's only aircraft carrier, the Liaoning. But Mr. Hagel's trip to China was short on friendly exchanges. The two sides spoke of cooperation, but openly disagreed about territorial disputes in East Asia.Secretary Hagel arrived in Beijing after a stop in Japan. He told reporters that China must reduce tensions with its neighbors and be more open about its military strength.China and Japan are involved in a territorial dispute over islands in the East China Sea. The islands are called the Diaoyu in China and Senkaku in Japan. They are rich in natural resources and provide valuable waters for fishing.A group of disputed islands, Uotsuri island (top), Minamikojima (bottom) and Kitakojima, known as Senkaku in Japan and Diaoyu in China is seen in the East China Sea, in this photo taken by Kyodo News Service, September 2012.Last year, China established an air defense identification zone over the disputed islands. China claimed the right to take military action against any aircraft without approval to fly over the area. Secretary Hagel criticized the decision to create the air defense zone over the islands."Every nation has a right to establish air defense zones, but not a right to do it unilaterally, with no collaboration, no consultation. That adds to tensions, misunderstandings, and could eventually add to, and eventually get to, dangerous conflict."China's Defense Minister strongly disagreed with the Defense Secretary. General Chang Wanquan noted that territorial issues are very important to his country. He said China would not incite Japan to action, but is prepared to protect its territory. In his words, "on this issue, we will make no compromise, no concession, no trading, not even a tiny bit of violation is allowed."This was the third time that Defense Minister Chang and Secretary Hagel have met since they each took office.This week, Secretary Hagel made a visit to China's National Defense University. He spoke about the need for openness as a way to avoid misunderstandings. One officer accused the United States of taking sides in Asia as a way to incite tensions and block the rise of China's military. The United States denies it wants to contain China.Jonathan Pollack is with the Brookings Institution, a Washington-based research group. He says U.S. officials have taken a somewhat harder line in how they deal with issues of importance to Asia.Secretary Hagel ended his 10-day trip to Asia with a visit to China's neighbor, Mongolia. He signed a new deal to provide more military training and assistance to Mongolia. The U.S. currently provides about $3 million in military sales and training to the country.Other nations have strengthened military ties with the United States. This has led China to criticize the U.S. for seeking to contain its rise. But observers say relations between the sides have improved over the past year or so. The two militaries have held several joint exercises since last year.And that's In The News from VOA Learning English. I'm Steve Ember.