Mike Mullen, chairman of the U.S. Joint Chiefs of Staff, wrapped up his four-day trip to China and departed from the eastern coastal province of Zhejiang on Wednesday after visiting a submarine base of the People's Liberation Army (PLA).

Mullen's China tour came after Chen Bingde, the chief of the PLA's General Staff, visited the U.S. in May.

"I think these visits and exchanges, not just between the leaders but also among military forces, have helped to clear up a lack of transparency. I regard them as a very positive step," Mullen said on Tuesday while watching a jet fighter training exercise in north China's Shandong Province.

"The relationship (between the United States and China) has just recently renewed, so we have a long way to go," Mullen said, adding that "I'm confident in the future of our military-to-military relationship."

Early this year, President Hu Jintao paid a state visit to the United States, during which he reached a consensus with U.S. President Barack Obama on jointly building a China-U.S. partnership that will feature mutual respect, mutual benefit and win-win cooperation.

During his stay in China, Mullen also watched an anti-terror drill and visited the Second Artillery Force, which is responsible for China's nuclear hardware.

"Mullen's visit highlighted the consensus reached between China and the United States and showcased the commitment that China holds toward boosting ties between the armed forces of both nations," said Qian Lihua, director of the Foreign Affairs Office with the Chinese National Defense Ministry.

On Monday and Tuesday, Mullen met with Vice President Xi Jinping, Vice Chairman of the Central Military Commission Guo Boxiong, Defense Minister Liang Guanglie and State Councilor Dai Bingguo.

Mullen held talks with his Chinese counterpart Chen Bingde on Monday morning after being received with a red-carpet welcoming ceremony.

The two generals held discussions on a variety of "sensitive" topics, including China's sovereignty in the South China Sea, the United States' sale of weapons to Taiwan, cyberspace security and China's military development.

"There are contradictions between China and the United States, some of which are even fundamental. However, neither of the countries can develop well without the other, as the two countries are highly interdependent," said Yao Yunzhu, a researcher with the PLA Academy of Military Science.

In addition to their general commitment to stepping up military-to-military relations, Mullen and Chen also agreed on several specific exchange plans during their talks.

The commander of one of the PLA's military regions will visit the headquarters of the U.S. Pacific Command in the third quarter of this year, while the U.S. commander-in-chief of the Pacific Command will visit China before the end of the year, according to a press release issued after the talks.

Hospital ships of the two navies will conduct exchanges and carry out joint medical and rescue drills, the release said.

Armed forces from both sides will conduct joint humanitarian rescue and disaster relief drills in the third quarter of 2012, according to the release.

The two navies will also carry out joint anti-piracy drills in the Gulf of Aden in the fourth quarter of this year. The two sides agreed to hold working group meetings and annual maritime military security meetings before the first half of 2012, the release said.

"We have been glad to witness the rejuvenation of bilateral military relations, as they are often hard-won and should be treasured," Chen said after the talks were concluded.

In January, former U.S. Defense Secretary Robert Gates came to China to pave the way for President Hu's state visit to the United States.

(Xinhua News Agency July 13, 2011)