China has practiced bombing runs on Guam U.S. military officials are concerned over China's increasing air power in the Asia-Pacific region. One activity by the Asian nation is proving especially worrisome.

JOINT BASE PEARL HARBOR-HICKAM, Hawaii — China has practiced bombing runs targeting the U.S. territory of Guam, one of a host of activities making U.S. forces here consider Beijing the most worrisome potential threat in the Pacific, even as North Korea pursues a nuclear warhead.

Beyond the well-publicized military build up on man-made islands in the South China Sea, China has built up its fleet of fighters to the extent that it operates a daily, aggressive campaign to contest airspace over the East China Sea, South China Sea and beyond, U.S. military officials in the region said. China has also taken several other non-military steps that are viewed as attempts to make it much more difficult for the U.S. to operate there and defend allies in the future.

The officials described the escalatory behaviors by China in a briefing they provided to reporters traveling with Chairman of the Joint Chiefs of Staff Gen. Joseph Dunford.

The officials said despite increased threats by North Korea as it pursues its nuclear weapons program, a conflict with North Korea is still viewed as “a fight we can win,” they said. With China, they said they “worry about the way things are going.”

China “is very much the long-term challenge in the region,” said Dunford, who was not part of the briefing. “When we look at the capabilities China is developing, we’ve got to make sure we maintain the ability to meet our alliance commitments in the Pacific.”

Over the last year Japan has scrambled 900 sorties to intercept Chinese fighters challenging Japan’s air defense identification zone, or ADIZ. In 2013 China announced borders for its own ADIZ, borders which overlapped Japan’s zone and included the disputed Senkaku Islands in the East China Sea. Since then, increased interactions between Japanese and Chinese aircraft ultimately resulted in Japan relocating two fighter squadrons to Naha Air Base on Okinawa to more easily meet the incursions, the officials said.

“We now have, on a daily basis, armed Chinese Flankers and Japanese aircraft” coming in close proximity of each other, the officials said, adding that intercepts between the U.S. and China are also increasing.

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“It’s very common for PRC aircraft to intercept U.S. aircraft” these days, the officials said, referring to the People’s Republic of China.

Chinese aircraft are also testing U.S. air defense identification zones, the officials said. Chinese H-6K “Badger” bombers upgraded with 1,000 mile range air launched cruise missiles are testing U.S. defense zones around Guam.

The Badgers run “not infrequent” flights to get within range of the U.S. territory, they said.

“The PRC is practicing attacks on Guam,” the officials said.

The vast majority of the flights occur without an incident, such as a report of unsafe flying, for example. The officials said they follow U.S. Pacific Command guidance on how to respond in those events, so they do not further escalate.

Military-to-military relationships between the U.S. and China remain open, if guarded, the officials said. Both Chinese and U.S. officials meet twice a year at the Military Maritime Consultative Agreement conference, where the incursions are discussed along with other security topics.

The expanded Chinese fighter and bomber runs are just one part of the country’s effort to “win without fighting” to gradually normalize the gains China has made in the South China Sea, the officials said.

There are other pressures. For example, the officials said they estimate the People’s Liberation Army Navy has placed as many as 150,000 Chinese commercial fishing vessels under its direction, even though they are not official Chinese navy. The Chinese fishing vessels make coordinated attacks on Vietnamese fishermen, the officials said, ramming and sometimes sinking boats near the Paracel Islands. China took the territory from Vietnam in the 1970s and has militarized some of the islands. The area remains a traditional fishing area for the Vietnamese.

Taken together, China’s activities suggest it is preparing to defend expanded boundaries, the U.S. officials worry.

“I think they will be ready to enforce it when they decide to declare the Nine-Dash line as theirs,” one of the officials said, referring to the territorial line China has identified that would notionally put the entire South China Sea under Chinese control if enforced.

If unchallenged, the U.S. officials worry that China could slowly force countries away from what they describe as the “rules based order” — essentially the standing international treaties and norms — in the region and make them shift their security alliances to Beijing for their own economic survival.

Dunford said the U.S. would not allow that to happen.

“We view ourselves as a Pacific power,” Dunford said.

“There are some who try to create a narrative that we are not in the Pacific to stay,” he said. “Our message is that we are a Pacific power. We intend to stay in the Pacific. Our future economic prosperity is inextricably linked to our security and political relationships in the region.”

While all of the officials stressed that there is no imminent danger of a conflict with China, U.S. forces in the region are rethinking what a Pacific fight would look like.

“If we find ourselves in conflict out there we will be under air attack,” the official said.

One concept they shared is “agile combat employment” — dispersing the U.S. advanced fighters concentrated at air bases in Japan and scattering them to 10-15 undeveloped and highly expeditionary airstrips on islands in the region. The dispersion would require the rapid dissemination of logistics support to keep those aircraft operating at their remote locations. The Air Force has already been practicing how to disperse the fuel, most recently in their Arctic Ace exercise, the officials said.

The idea would be that the aircraft would be so dispersed that it would make it difficult for China to prioritize what it would attack.

President Donald Trump will visit the Pacific region later this week, making stops in Japan, South Korea, China, Vietnam and the Philippines. Dunford said he expected that some of the security and economic concerns generated by the increased incursions and economic pressures by China would likely come up.

“If people want to view that as a focus on China they can. But it’s based on a rules-based international order,” Dunford said. “It’s focused on our ability to advance our national interests. We’re not going to compromise in that regard.”