China is using its growing economic strength to extend its military’s influence by taking on new missions and investing in more advanced weaponry, the Pentagon said Friday.

But the main focus of China’s military buildup continues to be directed toward weapons that would be used in a conflict over Taiwan, the self-governing island that China considers part of its territory.

“Even as the [Chinese military] is contending with this growing array of missions, preparing for contingencies in the Taiwan Strait remains the principal focus and driver of much of China’s military investment,” the Pentagon said in its annual report to Congress on China’s military strength.

The Pentagon report listed an array of weapons systems that China has been buying as part of its effort to take on new roles and missions in the world. The Chinese are developing new stealth aircraft and may have started work on their first domestically built aircraft carrier. Defense officials do not consider the Chinese carrier to be much of a threat to U.S. forces or allies because it would be exceedingly vulnerable to attack from U.S. submarines in the event of a conflict.

China is also investing in longer-range cargo aircraft and logistics capabilities that will allow it to perform missions beyond its territorial boundaries. Some of these missions, such as humanitarian relief and counter-piracy operations, are seen as positives by U.S. officials.

But the country is also investing in large numbers of more modern short-range ballistic missiles. And it is buying attack submarines that appear to be designed to keep back U.S. forces in the unlikely event of a conflict.

The Pentagon said it believes China spent as much as $180 billion on its military buildup last year, significantly higher than the $106 billion that it said it plans to spend this year. “Estimating actual . . . military expenditures is difficult because of poor accounting transparency,” the report said.

The report also said that China continues to be a major source of cyber-espionage and intrusive attacks. Citing Chinese writings, the Pentagon said that these intrusions indicate that China uses cyber-operations to collect strategic intelligence from the U.S. government and private companies.