U.S. Defense Secretary Leon Panetta was allowed a rare look inside a Chinese naval base on Thursday, as he finished up his three-day visit to China.

Panetta toured a Chinese warship and a submarine at the headquarters of the Chinese navy's North Sea Fleet in the eastern city of Qinqdao. He is the first Pentagon chief to visit the facility.

A senior U.S. defense official said Panetta also met with the fleet's commander, Vice Admiral Tian Zhong. He said the two discussed the importance of each country's navy and noted Washington's invitation for China to join a major maritime exercise in 2014.

But most of Panetta's tour of the sensitive naval base was off limits to journalists, who were instead sent on a tour of a local brewery.

Washington has repeatedly accused Beijing of not being transparent about its rapidly expanding military, which boasts 2.3 million members. But Panetta's trip has largely focused on improving military ties with China.

On Tuesday, Panetta told a group of Chinese cadets at a military academy that Washington's new military focus on Asia should not be viewed as an attempt to contain China, but to promote regional stability.

Many in China suspect that the Obama administration's shift toward Asia is aimed at curbing the power of the emerging world power. The so-called “pivot” includes plans to transfer Marines to Australia and shift 60 percent of U.S. naval forces to the Pacific by 2020.

Panetta is wrapping up his week-long Asian tour that also included a stop in Japan, which is involved in a heated dispute with China over a group of islands in the East China Sea. Later, Panetta will head to New Zealand to meet with the country's defense minister.