During a nearly two-hour address at a graduation ceremony for 4000 university students, the long-time ruler said he understood the submarines would be nuclear-fuelled and not nuclear armed.

He then went on to question why the Australian government did not accept his assurances about Cambodia’s Ream naval base.

The US and its allies suspect the facility, which is being upgraded with Chinese funding, will become a strategic military outpost for Beijing.

Biden raised concerns about Chinese activities at Ream as recently as November, when he met with Hun Sen on the sidelines of the East Asia Summit.

Cambodia has always denied the claims, maintaining it is having the base renovated including with a dry dock to improve its military capacity to confront other challenges at sea.

“A couple of days ago I spoke to the Australian ambassador [Justin Whyatt]. I understand that it is not the nuclear weapon but a nuclear-powered submarine. I understand that,” he said.

“But why you do not understand me, my explanation that I need to build capacity of the [navy] to protect sovereignty, to combat human trafficking in person, drug trafficking, illegal fishing, or transborder crimes in Cambodian waters?

“Cambodia has the right to implement her constitution, to defend her territory.

Loading

“Once again, Cambodia would like to re-emphasise that there is no presence of the Chinese army or any foreign army in Cambodia. Once the upgrade is complete, Cambodia will welcome all countries to pay a visit, and we can launch joint military exercises.”

Cambodia is a close partner of China and Hun Sen paid tribute to their “ironclad ties” during a visit to Beijing to meet with Chinese President Xi Jinping last month.

Beijing’s Belt and Road Initiative has a significant footprint in the country, with state-owned Chinese companies behind a multitude of projects including new airports and expressways, as well as dozens of casinos in Sihanoukville, the coastal city near the naval base.

If the People’s Liberation Army Navy was to get access to Ream, it would become just China’s second overseas military post, adding to one it already has it in Djibouti, and its first in the Indo-Pacific.

Loading

Last June, Albanese called on China to be open about its intentions for the naval base. Beijing has said it is simply helping Cambodia rebuild it.

“I am not crazy, allowing China to come to occupy Cambodia,” Hun Sen said on Thursday. “China is not crazy to come to occupy the Khmer naval base.”

In a statement, the Philippines, meanwhile, said it appreciated the three AUKUS parties keeping it abreast of developments.

“It is important that partnerships or arrangements in the Indo-Pacific region, such as AUKUS, support our pursuit of deeper regional cooperation and sustained economic vitality and resilience, which are essential to our national development and to the security of the region,” said the Philippines Department of Foreign Affairs.

“AUKUS should cooperate with the International Atomic Energy Agency to ensure that its activities observe the relevant international nuclear safeguards and non-proliferation standards.”

Loading

The Philippines has moved to strengthen defence with the US and push back harder against harassment and intimidation by Chinese vessels in the contested South China Sea since President Ferdinand Marcos jnr was elected last year.

The Philippines and the US will next month stage the largest ever edition of their joint Balikatan training exercise, with about 17,000 troops including a small contingent of Australian soldiers to take part.

Get a note directly from our foreign correspondents on what’s making headlines around the world. Sign up for the weekly What in the World newsletter here.