In this 2019 photo, military vehicles carrying DF-5B intercontinental ballistic missiles travel past Tiananmen Square during the military parade marking the 70th founding anniversary of People's Republic of China, on its National Day in Beijing.
CNN  — 

The US military believes that China has more than 500 operational nuclear warheads, surpassing earlier projections and it may be exploring the development of conventionally-armed long-range missiles that could reach the United States, according to a major Pentagon report on Beijing’s military prowess.

China is rapidly modernizing its military and using it as a means of projecting power across the Pacific region and ultimately around the globe, improving its ability to operate in all the domains of warfare, including the traditional land, air and sea, as well as nuclear, cyber and space.

The 2023 China Military Power report, released annually by the Defense Department, said that Beijing has also completed the construction of three new fields of long-range ballistic missiles silos as it builds out its options for delivering a nuclear warhead from different platforms.

“This obviously raises a lot of concerns for us,” said a senior defense official on Wednesday. “What we’d really like to see is for them to be more transparent about their nuclear buildup and also to see some greater willingness on their part to discuss the strategic stability and risk reduction issues with us. “

China is using newer reactors and processing facilities to produce plutonium for its nuclear weapons program, according to the report, even though Beijing publicly maintains that the technologies are for peaceful purposes only.

As part of the latest National Defense Strategy, the US has pointed to China as the “pacing challenge,” capable of competing with America in terms of its military might, economic power and international reach. Beijing already possesses a standing army of more than one million soldiers, the largest navy in the world by number of ships and the largest air force in the region.

China uses its military might to assert its claims of sovereignty in the South China Sea and beyond, including Taiwan. In 2022, the Chinese military increased its aggressive actions towards the independent island territory, including ballistic missile overflights, military aircraft flying into Taiwan’s aerial identification zone and major exercises near Taiwan. Though Chinese President Xi Jinping said he is seeking the peaceful unification of Taiwan with China, he has not renounced the use of military force to achieve his goal.

The growing aggression isn’t only pointed at Taiwan or China’s neighbors.

Chinese military pilots have ramped up their “coercive and risky” behavior against US aircraft flying over the East and South China in the last two years. In total, there have been more than 180 such incidents, including some in which the Chinese jets came to within 20 feet of US military aircraft.

“It’s a centralized and concerted campaign to perform these risky behaviors in order to coerce a change in lawful US operational activity,” Ely Ratner, the Assistant Secretary of Defense for Indo-Pacific Security Affairs, said Tuesday.

US defense officials are still frustrated by China’s unwillingness to engage in high-level military-to-military channels, but a defense official said on Wednesday that some communication continues at the working level.

“We did have the PLA defense attache in recently for a briefing on the unclassified summary of our cyber strategy,” he said. “We have also had recently, a meeting between [INDOPACOM Commander] Admiral Aquilino and a deputy chief of the PLA’s Joint Staff Department in Fiji. But again, from our perspective, it’s important that we have consistent open lines of communication across all these levels, including the most senior levels.”