Washington ? China’s ongoing military buildup remains focused on preventing Taiwan’s independence but is expanding to include other regional military goals, including securing the flow of oil from overseas, according to an annual Pentagon study issued Friday.

The 42-page report, required by Congress, found that Beijing’s investment in offensive military capabilities along the Taiwan Strait has continued unabated. It has deployed more than 100 additional short-range missiles in the region over the last year, to bring its total aimed at Taiwan to about 900. China also has 400,000 of its 1.4 million soldiers based in the three military regions opposite Taiwan, the study said.

But Beijing’s investment in military modernization – which might have reached as much as $125 billion last year, according to Defense Intelligence Agency, or triple the official $45 billion declared by Beijing – has produced military systems that enable China to project force well beyond its shores.

Of particular concern, the report said, was the increasing ability of the People’s Liberation Army’ to strike at an adversary’s forces in the Pacific Ocean, a clear reference to U.S. bases in Asia and American naval forces that constantly patrol the region and that would rush to Taiwan in the event of a Chinese invasion.

“The PLA appears engaged in a sustained effort to develop the capability to interdict, at long ranges, aircraft carrier and expeditionary strike groups that might deploy into the western Pacific,” the report stated.

In addition, the report said China is attempting to move its long-range nuclear forces out of vulnerable silos, basing them on more elusive submarines and ground-based mobile launchers. One new intercontinental nuclear missile, the DF-31, which can be moved overland to avoid enemy attacks, was put into initial operation last year, the report said.

The report reiterated the Pentagon’s concern about Beijing’s successful anti-satellite missile test in January, saying it appeared to be part of a broad strategy aimed at disabling enemy satellites. The report said China is going further, developing sophisticated satellite jammers as well as “directed energy” weapons, like lasers, that could disable U.S. satellites.

The Pentagon reiterated its concern that China’s continued buildup is occurring even as it refuses to explain why it is investing so heavily in new weapons systems, a “lack of transparency” that is forcing the U.S. military to improve its own air and naval forces as a “hedge” against unknown Chinese designs.