BEIJING - United States Chairman of the Joint Chiefs of Staff Admiral Mike Mullen finished his visit to China on Wednesday. During his four-day visit, Mullen was shown Chinese army, navy and air forces facilities, as well as the Second Artillery Force Headquarters. He also met with Vice-President Xi Jinping and several other high-ranking officials in China.

US Admiral Mike Mullen, chairman of the Joint Chiefs of Staff, sits in the cockpit of a Su-27 fighter at a People's Liberation Army Air Force base in Jining, Shandong province, on Tuesday. [Ng Han Guan / Associated Press]

He is the first person from the US military's top officials who had the opportunity to see the full range of the Chinese army.

Mullen's visit is a return visit of Chief of the General Staff of the People's Liberation Army (PLA) Chen Bingde's visit to the US in May. The visits show an unprecedented frankness and openness from both sides, a big change from the past.

In May, the two sides admitted that there are more opportunities than challenges.

Mullen's visit is an important indicator for Sino-US military exchanges. His visit has not only deepened Sino-US military relations, but also reached consensus in many ways. Mullen believes that with the growth of China's military power, there will be more interaction between the two militaries, which can be deeper and broader.

At the highest level of the US military, Mullen has made several cooperative plans with the Chinese military during this visit. They include joint anti-piracy drills in the Gulf of Aden and annual maritime military security meetings. The result of the visit, in other words, is bountiful.

In addition, Mullen mentioned in his speech that both China and the US are now in a period of reform, but China's rise does not mean America's decline. A rising and peaceful China has a positive meaning for the whole world, and the good order of the world and prosperity of Asia could not exist without China and the US being powerful and prosperous jointly, Mullen said.

However, it has to be said that matters of contention loomed during his visit. The military relations between China and the US haven't been stable since January, and both military officials have visited each other to ease that tension. However, Mullen's visit comes at a sensitive time as the US recently finished conducting joint drills with the Philippines in the South China Sea.

US media reported the drills as low profile, and the US military spokesman also played down the exercise, emphasizing it was "only within a small range and a low-level exercise". US forces also stressed that the timing of the drills and Mullen's visit is just a "coincidence", and the exercise will not cause an unpleasant atmosphere upon Mullen's visit to China. The explanation is understandable, but inevitably people won't see this as a "coincidence" since drills do exist.

When Mullen talked about the South China Sea issue at a news conference, he said that the US has "an enduring presence here, we have an enduring responsibility. We seek to strongly support the peaceful resolution of these differences".

No matter how the US attempts to gloss over its drills, no one can deny that the US continues to maintain its military presence in the South China Sea.

There is a still a long way to go to improve the Sino-US military relations. When Mullen made a speech at Renmin University of China during his visit, he said China has become a powerful country that has a global influence, and therefore should bear the responsibility to match its growing ability. Mullen also said Chinese and US militaries should respect each other and have a global mind, they should work together to address the Korean Peninsula issue, nuclear proliferation, fair use of the high seas and global energy issues.

He gave three suggestions: First, have mutual respect for each other; second, focus on regional and global issues; third, look to the future. However, because of various issues, such as the US arms sale to Taiwan, there is still a long way to go to improve the Sino-US military relations.

The author is military specialist with the National Defense University of the PLA.