Washington ? China is boosting its missile stocks and military budget to prepare for what could be a quick and brutal showdown with Taiwan — and to prevent U.S. forces from getting in the way, the Pentagon said Wednesday.

Defense officials said China was emphasizing a “surprise, deception and shock” doctrine in its campaign against Taiwan, which Beijing considers a renegade province.

“Preparing for a potential conflict in the Taiwan Strait is the primary driver for China’s military modernization,” the Pentagon said in its annual evaluation of China’s military.

While focusing on Taiwan, China is developing weapons systems that would impede U.S. intervention on behalf of the island in any future conflict, the report found.

“Beijing apparently believes that the United States poses a significant long-term challenge. China’s leaders have asserted that the United States seeks to maintain a dominant geostrategic position by containing the growth of Chinese power, ultimately ‘dividing’ and ‘Westernizing’ China,” the report said.

The Chinese Foreign Ministry in Beijing had no immediate comment on the report.

China has about 450 short-range ballistic missiles but is expected to increase its inventory by more than 75 missiles each year, defense officials reported. Last year, the Pentagon estimated that China’s military had acquired 350 ballistic missiles and was adding at a rate of 50 a year.

The annual report is required by Congress to help keep lawmakers apprised of Beijing’s military strategy.

According to this year’s report, China has amassed missiles more sophisticated and accurate than before, with its army developing longer-range models of the CSS-6 missile capable of reaching as far as Okinawa, Japan, where U.S. Marines are based.

China also is spending far more on its defense budget than it has acknowledged. U.S. officials estimate the military budget that Beijing announced as $20 billion early last year actually falls between $45 billion and $65 billion.

Taiwan split from the mainland in 1949 after Nationalist Chinese leaders fled there following the communist victory in China.