China's potential to influence security arrangements in Papua New Guinea has been sidelined with a 10-year deal to launch an NRL team in Port Moresby.
The federal government is putting $600 million over a decade towards the unnamed PNG rugby league team that will take the field in 2028.
But a parallel agreement commits PNG to keeping Australia as its primary policing and security partner and not breaking "strategic trust".
It's unclear what that is defined as or what actions constitute a breach of the unpublished pact.
But it essentially locks China out of establishing any security or policing presence as Australia works to deny Beijing a foothold in the Pacific.
Pacific Minister Pat Conroy confirmed the clause existed but didn't elaborate, saying he was confident the trigger to extinguish the team wouldn't be needed.
"The agreement does contain a clause for the commonwealth government to withdraw its funding, that is true, but I'm very confident that will never happen because that strategic trust will endure in perpetuity," he told Sky News.
That the two nations were only separated by four kilometres at the closest point meant the security of one was paramount to the other, Mr Conroy said.
"We've made no secret of the fact we're facing permanent competition in the region for influence and to be partner of choice for the Pacific," he said.
"That's vital to our security."
The deal benefited both countries, Lowy Institute Pacific fellow Oliver Nobetau said.
"It's essentially a good deal for both, it's reflective of what each country wanted," he told AAP.
There had been heightened geo-politics in the Pacific in recent years, he noted, as China and the United States tussled for influence.
"One of the things that middle and major powers haven't been able to get is exclusivity of security partnerships," he said.
But he questioned the goodwill between Canberra and PNG if such a security agreement needed to be formalised as Australia worked to increase its diplomatic influence in the region.
PNG Foreign Minister Justin Tkachenko has ruled out entering a security agreement with China as Beijing works to gain a foothold in the Pacific after signing a policing agreement with the Solomon Islands.
Thursday's announcement came the same day a separate Australia-PNG security agreement came into force
The pact commits both nations to maintain and strengthen co-operation in defence, policing, national security, climate change and disaster relief.
Prime Minister Anthony Albanese defended the deal's text being kept secret alongside PNG counterpart James Marape in Sydney on Thursday when announcing the football deal.
The parallel pact affirmed Australia was the security partner of choice, which was reflected in the bilateral agreement that was public, Mr Albanese said.
"It's certainly not a secret that our relationship is so strong that we work together and part of that working together is because of our common values," he said.
The agreement didn't preclude relations with other countries and China would remain a strong trading partner but security arrangements needed to be unique with countries PNG shared borders with, Mr Marape said.
