China is secretly building a naval facility in Cambodia for the exclusive use of its military, with both countries denying that is the case and taking extraordinary measures to conceal the operation, Western officials said.

The military presence will be on the northern portion of Cambodia’s Ream Naval Base on the Gulf of Thailand, which is slated to be the site of a groundbreaking ceremony this week, according to the officials, who, like others, spoke on the condition of anonymity because of the matter’s sensitivity.

The establishment of a Chinese naval base in Cambodia — only its second such overseas outpost and its first in the strategically significant Indo-Pacific region — is part of Beijing’s strategy to build a network of military facilities around the world in support of its aspirations to become a true global power, the officials said.

China’s only other foreign military base right now is a naval facility in the East African country of Djibouti. Having a facility capable of hosting large naval vessels to the west of the South China Sea would be an important element of China’s ambition to expand its influence in the region and would strengthen its presence near key Southeast Asian sea lanes, officials and analysts said.

“We assess that the Indo-Pacific is an important piece for China’s leaders, who see the Indo-Pacific as China’s rightful and historic sphere of influence,” one Western official said. “They view China’s rise there as part of a global trend toward a multipolar world where major powers more forcefully assert their interests in their perceived sphere of influence.”

Beijing, the official said, is banking on the region being “unwilling or unable to challenge China’s core interests,” and through a combination of coercion, punishment and inducements in the diplomatic, economic and military realms, believes it can get countries to bend to its interests. “Essentially, China wants to become so powerful that the region will give in to China’s leadership rather than face the consequences [for not doing so],” the official said.

The Wall Street Journal reported in 2019 that China had signed a secret agreement to allow its military to use the base, citing U.S. and allied officials familiar with the matter. Beijing and Phnom Penh denied the report, with Cambodian Prime Minister Hun Sen denouncing it as “fake news.” A Chinese Defense Ministry spokesman at the time also denounced what it called “rumors” and said China had merely been helping with military training and logistical equipment.

Over the weekend, however, a Chinese official in Beijing confirmed to The Washington Post that “a portion of the base” will be used by “the Chinese military.” The official denied it was for “exclusive” use by the military, saying that scientists would also use the facility. The official added that the Chinese are not involved in any activities on the Cambodian portion of the base.

The official said the groundbreaking, scheduled for Thursday, was taking place and that Chinese officials would attend. The Chinese ambassador to Cambodia is expected to be present.

Asked for comment, the Cambodian Embassy in Washington said in a statement that it “strongly disagrees with the content and meaning of the report as it is a baseless accusation motivated to negatively frame Cambodia’s image.” It added that Cambodia “firmly adheres” to the nation’s constitution, which does not permit foreign military bases or presence on Cambodian soil. “The renovation of the base serves solely to strengthen the Cambodian naval capacities to protect its maritime integrity and combat maritime crimes including illegal fishing,” the statement said.

China’s Foreign Affairs Ministry did not reply to a request for comment.

The Western officials said they expect there will be an acknowledgment at the ceremony of Chinese involvement in financing and construction of the expansion of Ream Naval Base, but not of plans for its use by the People’s Liberation Army. The expansion plans were finalized in 2020, and, significantly, called for the Chinese military to have “exclusive use of the northern portion of the base, while their presence would remain concealed,” a second official said.

The two governments have taken pains to mask the presence of the Chinese military at Ream, the official said. For instance, foreign delegations visiting the base are permitted access only to preapproved locations. During these visits, Chinese military personnel at the base wear uniforms similar to their Cambodian counterparts’ or no uniform at all to avoid suspicion from outside observers, the official said. When Deputy Secretary of State Wendy Sherman visited the base during a trip to the region last year, her movements were “very heavily circumscribed,” the official said.

While she was in Cambodia, Sherman sought clarification over Cambodia’s razing in 2020 of two U.S.-funded facilities on Ream Naval Base, according to a State Department news release. The demolition took place after Cambodia declined a U.S. offer to pay to renovate one of them, according to a Pentagon report on Chinese military developments last year. That move, the report said, “suggests that Cambodia may have instead accepted assistance from the [People’s Republic of China] to develop the base.”

“What we’ve seen is over time is a very clear and consistent pattern of trying to obfuscate and hide both the end goal as well as the extent of Chinese military involvement,” the second official said. “The key thing here is the [PLA’s] exclusive use of the facility and having a unilateral military base in another country.”

Last year, the “Joint Vietnamese Friendship” building, a facility built by the Vietnamese, was relocated off Ream Naval Base to avert conflicts with Chinese military personnel, the officials said. China and Vietnam have long had a tense relationship, with Hanoi and Beijing clashing over competing territorial claims in the South China Sea for half a century.

The secrecy around the base appears to be driven primarily by Cambodian sensitivities and concern about a domestic backlash, the second official said. There is strong domestic opposition to the idea of a foreign military base, said the official, noting the constitutional ban on the presence of foreign military in the country. As the chair of the 10-member regional Association of Southeast Asian Nations (ASEAN) this year, Cambodia is keen to avoid the perception it is, as the second official said, “a pawn” of Beijing.

Cambodia has been walking a fine line between accommodating and distancing itself from Beijing. It was an “enthusiastic supporter” of the U.S.-ASEAN special summit in Washington last month, the second official said. In March, it joined 140 other countries in voting at the U.N. General Assembly to condemn Russia’s invasion of Ukraine. Beijing abstained from the vote and has publicly affirmed a “no limits” partnership with Moscow that includes opposing further NATO enlargement. At the same time, Chinese influence in Cambodia has grown rapidly in recent years, with China providing substantial aid and investment, a trend that has also caused some concern in Phnom Penh about overreliance on Beijing.

Beyond its base in Djibouti, opened in 2017, Beijing is pursuing military facilities to support “naval, air, ground, cyber, and space power projection,” the Pentagon report said. It has “likely considered a number of countries,” it said, listing more than a dozen, including Cambodia, Thailand, Singapore, Indonesia, Pakistan, Sri Lanka, Tanzania and the United Arab Emirates. A global network could “both interfere with U.S. military operations and support offensive operations against the United States,” the report said.

The report also said that Chinese military academics have asserted that such bases can enable deployment of military forces in theater, and intelligence monitoring of the U.S. military.

The Chinese official told The Post that ground station technology for a BeiDou navigation satellite system was located at the Chinese portion of Ream Naval Base. BeiDou is China’s homegrown alternative to the U.S. Space Force-managed Global Positioning System, and has military uses including missile guidance. The official did not have direct knowledge of how this system was being used.

China’s military uses BeiDou’s high-accuracy positioning and navigation services to facilitate force movements and precision-guided munitions delivery, according to a March report by the Pentagon’s Defense Intelligence Agency.

China’s global basing effort is “not just about power projection but about global tracking and space assets,” said a third Western official. Cambodia’s Ream is “one of their most ambitious efforts to date.”

China’s navy is already the world’s largest by numbers of vessels. The U.S. Navy has 297 battle-force ships — carriers, destroyers, submarines, etc. — according to the Congressional Research Service, while China has 355 and is projected to have 460 by 2030, according to last year’s Pentagon report.

But, said Andrew Erickson, research director of the China Maritime Studies Institute at the Naval War College, “as impressive as those numbers are, without a significant network of robust overseas facilities, their ability to use them falls off rapidly with distance from China.”

China is nowhere close to matching the network of military bases the United States has around the world, a major U.S. military and strategic advantage, said Richard Fontaine, chief executive of the Center for a New American Security. But, he said, a base in Cambodia “gives them a force-projection capability that they would otherwise not have in the region. That’s intrinsic to the Chinese aspiration of having a more dominant military presence throughout the Asian rimland and in the South China Sea, allowing Beijing to hold at risk — and have political influence over — countries quite far from the Chinese shore.”

Djibouti was a logical first step for a military outpost in that it is in a region far from China in which Beijing wants to have a presence, in this case to secure its growing Middle Eastern energy interests, Erickson said. Also, the United States, France and Japan have long had military bases there, he noted. “The question then becomes, how do you start filling out the board?”

Cambodia is “a no-brainer” in that Hun Sen, prime minister since 1985, is “extremely amenable,” Erickson said, noting that the Cambodian leader has had a long strategic partnership with Beijing.

“But the problem is Cambodia is a small country in a tough spot,” he said. “It’s trying to have it both ways: maximum strategic collaboration with China with minimum regional pushback. That contradiction is going to be exposed by the undeniable development of this facility.”

China also has reportedly sought to establish a facility in the UAE. Last year, U.S. intelligence agencies learned that Beijing was secretly building a military installation at a port in near the Emirati capital of Abu Dhabi, the Wall Street Journal reported. After meetings and visits by U.S. officials, construction was halted, the Journal reported. The current status of the project is unclear.

China’s secret building of a Cambodian base “resembles the playbook” it used in reclaiming and militarizing the Spratly Islands in the disputed South China Sea beginning in 2015, said Eric Sayers, a former adviser to the U.S. Indo-Pacific Command who is now a nonresident fellow at the American Enterprise Institute. “It started quietly,” he said, “with Beijing claiming its building of artificial islands on coral reefs and atolls was for peaceful purposes and promising the features would not be militarized. Then when it was far too late, we saw permanent and irreversible militarization.”

He said he expected to see the trend also play out in the Solomon Islands, a South Pacific nation that recently signed a security agreement with China. In April, after a draft copy of the agreement was leaked on social media, Beijing confirmed the pact, which neither government has released. According to the leaked copy, China will be permitted to send armed police and military personnel to the Solomon Islands to help maintain order. The government there has denied it would lead to China establishing a military base.

But Western officials are skeptical. “There’s evidence that China is developing plans and has sent technical teams to the Solomons to explore possibilities for basing facilities that would contradict some of the assurances that the government has made to allied governments,” a third Western official said.

The Solomons agreement is part of a broader Chinese effort — not always successful — to build influence in the region. Last week, China’s top diplomat, Wang Yi, completed a 10-day tour of the South Pacific but failed to achieve a desired 11-nation pact on security and development. Instead of repeating the Solomons diplomatic coup, China’s proposal was shelved at a meeting in Fiji, after some countries questioned whether the deal would spark greater confrontation between China and rivals in the region.

But it would be a mistake to take the rebuff of Wang as a sign that Beijing’s influence is waning, the third official said. “There is a relentless quality to what the Chinese are involved in and they’re just going to keep coming. So anyone who thinks this is a signal that they’ve been blunted or blocked, that’s not accurate.”

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The Washington Post’s Alice Crites in Washington and Eva Dou in Shenzhen, China, contributed to this report.