Austin expresses concern over Cambodia's growing relationship with China

U.S. Secretary of Defense Lloyd Austin met with Cambodia's prime minister Tuesday amid concerns in Washington over the kingdom's relationship with China, which may look to the country as a foothold in southeast Asia.

The Pentagon chief, who met with Prime Minister Hun Manet for the first time since he took over the premiership from his father, expressed concerns over Beijing's involvement with the naval base it helped build, a U.S. official told ABC News.

Cambodia, a close ally of China, allowed it to build the base on the Gulf of Thailand with Chinese funds. Chinese warships were spotted there as recently as last month.

Austin met with Manet and his father Hun Sen, who ruled the country for 38 years, separately, the Pentagon said. Manet is an alumnus of the United States Military Academy at West Point, the first Cambodian cadet to graduate West Point and Austin's alma mater as well.

Both the American and Cambodian sides signaled optimism about the talks in Phnom Penh -- with the U.S. readout pointing to "opportunities" for cooperation despite work-in-progress on the base.

Deputy Prime Minister Sun Chanthol told ABC News ahead of the meeting that talks could produce "military-to-military" relations that would include joint exercises on humanitarian and disaster relief, demining, and collaborating on recovering remains of American service members missing in action in Cambodia.

Ream, which the deputy prime minister acknowledged was a military base, will be open to foreign navies aside from China for exercises, he said.

"It is absolutely not a Chinese facility," Sun said in an interview with ABC News. "We built Ream Naval Base for our own national security."

"When it's complete, any navy in the world that wants to call on [Ream] for humanitarian, for disaster recovery, whatnot, please, okay, you can use it," he said.

Whether the Cambodians allow other navies to use the base, and whether builders continue dredging, will be crucial in telling if Ream is a Chinese base, according to an analysis by the Center for Strategic and International Studies.Sun confirmed dredging was happening at the base, but reiterated that any navy who uses it will not be allowed to do so for military purposes.

"We will not allow our territory to be used by any military to attack another nation," he said, citing Cambodia's cosponsorship of the resolution opposing Russia's invasion of Ukraine.

A Pentagon spokesperson told ABC News that "there are no doubts about where our concerns are."

"Meeting face-to-face gives us a chance not only to speak clearly about our concerns, but to talk about how we might work together in the future to strengthen our relationship," the spokesman said.

"And we don't ask any country to choose between partners," they added.

Sun said Cambodia's relations between Beijing and Washington are not a "zero-sum game" and that it can trade with both – and that the US is already the top exporter to Cambodia.

"We need more, not less U.S. investment. We need more engagement with the U.S. -- not less," said Sun, who is courting foreign direct investment from Japan and Europe, too.

Cambodia is qualified by the United Nations as a least developed country but is on track to graduate from that status by 2029.

"It's definitely clear that the new prime minister is great for attracting more [foreign direct investment] from the west," said Allen Tan, a former president of the American Chamber of Commerce in Cambodia.

The regulatory environment in the kingdom is increasingly aligning with expectations of western investors, Tan said, and the U.S. already leads on demining in Cambodia and globally.

Minister Sun said he hoped Austin and Manet would have "heart-to-heart" conversations and that Cambodia, suffering under conditions he likened to starvation, partners with Beijing out of necessity.

"China built that port just because we don't know how to build a port," he said of Ream.

A senior defense official told ABC News said Austin values talking "face-to-face, especially in this part of the world" and that "there's a lot our two countries can do together."

"Cambodia is a young country in a young region. Our defense relationship has a lot of potential and room for growth," the official said, naming the possibility of resuming military training and exchanges.