OMAHA—China is aggressively building up nuclear warfighting forces as part of a larger effort to expand power over Asia and globally, according to senior officials of the U.S. Strategic Command.

Vice Admiral David Kriete, deputy commander of the command, said he is concerned by China's rapidly growing nuclear arsenal when combined with other alarming activities in the South China Sea and elsewhere.

"China is and has been for the last couple of decades on a very clear trajectory where they're increasing the numbers of nuclear weapons that they field, they're increasing the number of and diversity of the delivery systems," Kriete said in a press briefing.

"They are working on fielding a triad—ballistic missile submarines, strategic bombers, and land-based intercontinental ballistic missiles."

In addition to a delivery system, Beijing is expanding its nuclear weapons production capabilities that will "allow them to continue on this trend or actually increase it in the future should they so choose," the three-star admiral said.

Regional missile systems that do not have the same range as strategic missiles are being fielded.

Kriete also questioned China's declared no-first-use policy, the statement that Chinese military forces would not be the first to use nuclear arms in a conflict.

"When it comes to the no-first-use policy, I have read about this no-first-use policy," he said. "Beyond that statement, they don't talk much about it, so I'm not exactly sure what it is."

Kriete said the nuclear buildup should be viewed within the context of China's regional and global expansion.

"China's leadership has made it clear in recent years that they have goals of becoming a regional power and exerting—economic and military—over the western Pacific at some point in the future," he said. "And then obtaining some level of global influence at some point after that."

Chinese military activities in the western Pacific are supporting those goals.

Also troubling are China's militarization of disputed islands in the South China Sea.

China has reclaimed some 3,200 acres of islands and last year was detected deploying anti-ship and anti-aircraft missiles on them, along with electronic warfare capabilities.

Kriete said Stratcom is not focused on deterring regional conflicts with China but supports the Indo-Pacific Command in its efforts to do so.

"At the same time we'll work on that strategic deterrent effect vis a vis China as well as Russia and some other countries," he said.

China's buildup of nuclear forces includes several new mobile nuclear missiles, including the DF-41 that is being deployed with multiple warheads. New ballistic missile submarines are being deployed along with a new strategic bomber.

China is believed to have more than 200 warheads for strategic weapons. However, Chinese secrecy has prevented knowing the precise numbers of warheads, which could be as high as 1,500.

China also is nearing deployment of a hypersonic glide vehicle—a maneuvering ultra-high-speed missile that can defeat missile defenses.

The admiral stressed that the United States does not want a war with China or any other country but needs to be prepared to do so.

"We really want a peaceful coexistence in a lot of places around the world, and I think there are ways to achieve that," he said. "The strength that we show through our military force in the region and really domestically back home is an important part of that face that we show to China and other countries around the world."

Another official, Rear Adm. Michael Brookes, director of intelligence for the command, said China's nuclear forces modernization is a concern.

"China has long had a no-first-use policy, and yet they've doubled their nuclear arsenal in about the last decade, and they're on track to double it again in the next decade," Brookes said during a Stratcom conference on deterrence.

"It's a little bit concerning the breathtaking pace of change with regard to their arsenal," he said.

Combined with the nuclear buildup, Chinese leaders "appear to have a disinterest, at least at this time, to submit to any arms control regime."

The Trump administration has said it is seeking to include China in a three-way or bilateral arms control regime. Beijing's military has rejected entering into any negotiation on its nuclear forces over concerns that the talks would undermine its deterrent value.

Brookes said another concern regarding the Chinese nuclear buildup, as well as Russia's nuclear modernization, are worries about their buildup of cyber warfare, space warfare and electronic warfare capabilities that could impact U.S. nuclear deterrence.

These weapons "fan the flames of competition" and jeopardize "the U.S.'s ability for indications and warning and C2 [command and control] of our nuclear forces," Brookes said.

"That's viewed as somewhat destabilizing and inflammatory," the intelligence director said.

The Stratcom officials' comments reflect warnings issued in May by Army Lt. Gen. Robert Ashely, who warned that China also is stepping up nuclear testing by operating a test facility year round.

Ashely called the nuclear modernization "the most rapid expansion and diversification of its nuclear arsenal in China's history."

China's nuclear forces remain couched in secrecy. China operates large-scale underground nuclear storage and production facilities in a tunnel system dubbed the Great Underground Wall.

The system is estimated to include more than 3,000 miles of tunnels and underground plants.

On the topic of extending the New START arms treaty past its 2021 deadline, Kriete said Russia is building new strategic weapons and capabilities that are not covered by the treaty and that pose risks to deterrence.

Moscow has announced the development of a nuclear-powered cruise missile, hypersonic glide vehicles, and a nuclear-tipped underwater drone.

North Korea and Iran also are worried about their nuclear forces.

Stratcom is also assisting with the development of a new warfighting command, the Space Command, that will take over military space and defense responsibilities from Strategic Command. The new command could be stood up in the coming weeks, Kriete said.

Regarding U.S. nuclear forces modernization, Kriete said the military is moving ahead with a new Ground Based Strategic Deterrent—a nuclear missile to replace aging Minuteman III ICBMs.

Kriete said there are no current plans to deploy the new ICBM in a road-mobile launcher, but he did not rule out that mobile basing for U.S. strategic missiles could be used in the future.