The first Chinese warships have docked at a newly expanded Cambodian naval base. Should the US be worried?

Chinese warships have docked for the first time at Cambodia’s Ream Naval Base, which is undergoing a Chinese-funded upgrade that has drawn concerns from the United States over its potential role in expanding China’s overseas military footprint.

Cambodia’s Defense Minister Tea Seiha visited the Chinese People’s Liberation Army (PLA) Navy warships docked at the Ream port on Sunday along with his father – and predecessor – Tea Banh, according to a post on the official’s Facebook page.

While the post did not specifically mention the Chinese military, the accompanying photos showed two PLA Navy corvettes docked side by side. On board one of the corvettes, identified as the “Wenshan” on the vessel’s gangplank, Tea Banh reviewed a row of Chinese naval officers.

The ships are in preparation for training the Cambodian navy, according to the post.

Other photos in the post show the father and son inspecting infrastructure construction on the site and viewing a design plan of the project.

Collin Koh, research fellow at the S. Rajaratnam School of International Studies (RSIS) in Singapore, said according to public records, this is the first time PLA Navy ships have docked at the port, which before renovation was only fitted for the Cambodian Navy’s smaller patrol crafts.

“It is a signal that Ream is about to be completed. Of course, it’s still work in progress for them, but at least now, it has expanded to the point that it could accommodate a foreign navy ship,” he said.

John Bradford, executive director of the Yokosuka Council on Asia-Pacific Studies, said it is no surprise that Chinese ships were the first to visit the upgraded base.

“After all, the facilities were funded by the Chinese and China is a close partner to Cambodia,” he said.

The visit of Chinese warships coincided with a top Chinese general’s trip to Phnom Penh, where he hailed China and Cambodia as “true ironclad friends.”

He Weidong, a vice chairman of China’s top military body, the Central Military Commission, told Cambodian Prime Minister Hun Manet that the two countries’ militaries have sustained “high-level cooperation in fields including high-level exchange, mechanism building, joint drills and exercises, and personnel training,” according to a Chinese readout of the meeting.

Hun, who succeeded his father Hun Sun earlier this summer, thanked the Chinese military for its “strong support for the modernization of the Cambodian army,” according to the statement posted on the Chinese Defense Ministry’s website.

The Chinese general also held talks with Tea, the Cambodian Defense Minister, to exchange views on “bilateral relations, military cooperation, and international issues of common interest,” according to the readout, which did not mention the visiting PLA Navy warships.

CNN has reached out to China’s Ministry of Defense for comment.

A US State Department spokesperson said Washington was monitoring reports of the Chinese warships, according to Reuters. “While we have no comment on this specific development, we have serious concerns about the PRC’s plans for exclusive control over portions of Ream Naval Base,” the official told Reuters, referring to China by its official name, the People’s Republic of China.

Heightened concerns

The unprecedented presence of Chinese navy ships at the Ream Naval Base, which occupies a strategic position near the southern tip of Cambodia close to the South China Sea, is likely to deepen long-standing concerns among US officials that China is seeking a military outpost in the Gulf of Thailand.

Such concerns were already heightened in June last year, when Chinese and Cambodian officials presided together over a ground-breaking ceremony for a project to renovate the port with grant aid from China.

Cambodian officials have repeatedly denied the facility would be used by China as a naval base, insisting the project is in line with Cambodia’s constitution, which bars foreign military bases on its territory. Chinese officials, meanwhile, have described the base as an “aid project” to strengthen Cambodia’s navy and called assertions otherwise “hype” with “ulterior motives.”

For the US, the Chinese-funded expansion at Ream is particularly troubling as it involved the demolishing of a US-funded facility there — a development that served as something of an analogy for Cambodia’s closer ties with Beijing and growing distance from Washington, according to Bradford at the Yokosuka Council.

For some, the visiting Chinese navy ships have raised new alarms.

“The arrival of these Chinese warships at Ream exposes China’s long-concealed military aims, marking a major evolution in China’s regional defense posture. To continue dismissing China’s expanding military footprint is to indulge in self-delusion,” said Craig Singleton, a senior fellow at the Washington-based think tank the Foundation for Defense of Democracies.

Singleton, who wrote an analysis on Beijing’s growing push for overseas port access earlier this year, said China’s presence at the Ream Naval Base is part of a broader plan to complicate America’s global military calculus.

“By building closer military ties and economic dependencies with select countries along major maritime routes, Beijing can exert diplomatic pressure on them, limiting U.S. basing access and complicating coalition-building efforts to support Taiwan’s defense should China ever invade,” the self-ruled island Beijing claims as its own, he said.

Alongside Djibouti in East Africa, Beijing’s sole military base overseas, Ream “signals more than just a cost-effective extension of China’s defense perimeter, but a calculated, assertive repositioning with grave implications for Washington and its allies.”

But other experts have noted that the level of access the PLA is granted at Ream could be very different from its base in Djibouti, where Chinese troops can be permanently stationed at onshore facilities. That arrangement would be a violation of Cambodia’s constitution, said Koh at the RSIS.

“There are many other types of access arrangements that don’t amount to or fall short of a real base agreement,” Koh said, such as allocating certain piers solely for Chinese navy use or ensuring the PLA Navy can be accommodated when it visits.

“I think there’s a lot of it being overblown that it’s a base for the Chinese. I don’t think that’s the case,” he said.

Cambodia has also appeared to be open to allow other foreign delegations to visit Ream – seen as part of its effort to refute accusations it is granting the Chinese military exclusive access to the naval base. Last March, a Japanese navy delegation visited the base.

“Until we could see going forward, whether the Cambodians only allow the Chinese navy to dock at the base, or they will allow other foreign navies to dock, we cannot come to a very easy conclusion that it is arranged only for exclusive Chinese access,” Koh said.

Military implications

But even if Ream will not be used to exclusively and permanently station Chinese forces, gaining regular access to it could have implications for military operations related to the South China Sea dispute between China and the Southeast Asian claimants.

Beijing claims “indisputable sovereignty” over almost all of the South China Sea, and most of the islands and sandbars within it, including many features that are hundreds of miles from mainland China. The Philippines, Malaysia, Vietnam, Brunei and Taiwan also hold competing claims.

“Ream would provide PLAN forces with an additional axis for attack and resupply in the case of a South China Sea conflict. Furthermore, bases on the Asian mainland would possibly be more easily resupplied, more resilient, and more capable than those established on relatively remote reclaimed features,” said Bradford, the analyst.

But he noted that the facilities in Cambodia would not be a “game-changer” in a South China Sea struggle.

“The distance (from) Ream to the Spratly Islands is greater than the distance from the Spratly Islands to major PLA bases on Hainan island,” he said, referring to the southernmost Chinese province and the disputed archipelago in the South China Sea where Beijing has built military installations on manmade islands.

Chinese forces operating from Cambodia would have to fly over Vietnam or detour south to pass between Vietnam’s southern tip and the northeast corner of Peninsular Malaysia, making this line of attack vulnerable to interdiction, Bradford said.

But Ream also allows the Chinese navy to dock much closer to the southern South China Sea – an important factor in China’s growing operations in Indonesia’s Natuna Sea and Malaysia’s Economic Exclusion Zone, said Carl Schuster, a former director of operations at the US Pacific Command’s Joint Intelligence Center.

“This new naval base exceeds Cambodia’s present requirements, but its significance is more geo-strategic than purely military. It signifies the Sino-Cambodian defense relationship and adds to Vietnam’s concerns about being encircled by China,” Schuster said.

CNN’s Simone McCarthy, Brad Lendon and Beijing bureau contributed reporting.

For more CNN news and newsletters create an account at CNN.com