Australia and Papua New Guinea will be legally obliged to defend each other from a military attack on either territory under a landmark defence treaty, the ABC can reveal.

The agreement will also give the Australian Defence Force unimpeded access to a series of designated facilities and areas within Papua New Guinea.

PNG’s cabinet endorsed the high-level security pact yesterday, on the eve of the country’s 50th anniversary of independence.

The deal, which is expected to be signed tomorrow, will be known as the Pukpuk Treaty — referring to the Papua New Guinean pidgin word for “crocodile”.

“The treaty is meant to prepare our militaries to be battle-ready and for a very bad day,” a PNG cabinet submission seen by the ABC said.

“It has the ability to bite and like a crocodile, its bite force speaks of the interoperability’s and preparedness of the military for war.”

Soldiers in camo lean next to a vehicles holding guns.

The treaty will allow PNG soldiers to serve in the Australian Defence Force and vice versa. (ABC News: Lincoln Rothall)

PM says he has ‘moral obligation’ to build military

The contents of the treaty have not yet been made public yet but the ABC has seen a copy included in a submission to PNG’s national cabinet this month.

It says both parties recognise an armed attack on either country would be “dangerous to the other’s peace and security”, with a promise to “act to meet the common danger”.

Last week, PNG Defence Minister Billy Joseph told the ABC the agreement would see the two countries’ militaries become “totally integrated forces”.

It will also enable Australia and PNG to recruit citizens from each other’s countries into their defence forces.

Two men in suits laugh with each other while standing behind lecterns at a press conference

James Marape, pictured with UN secretary-general Antonio Guterres earlier this month, says his priority is strengthening PNG. (ABC News: Lincoln Rothall)

On Monday, Papua New Guinean Prime Minister James Marape told journalists his key concern was increasing the capacity of the Papua New Guinea Defence Force.

“If someone chose to invade our country right now, as your prime minister, I don’t have the capacity to defend you,” he said at a press conference.

“I have a moral obligation to build my military to a level that I can have the capacity to defend Papua New Guinea, every child.”

Collaboration around cyberspace and electromagnetic warfare

The treaty being finalised comes at a time of increasing geo-strategic competition in the Pacific between Australia, the United States and China.

It also comes as Papua New Guinea marks 50 years of independence from Australia, Britain and Germany, with celebrations taking place across the country today.

Australian Prime Minister Anthony Albanese, Deputy Prime Minister Richard Marles, and Minister for the Pacific Pat Conroy arrived in PNG on Monday, ahead of the festivities.

Anthony Albanese wearing a suit with a lei around his neck.

Anthony Albanese arrived in Port Moresby on Monday. (AAP: MiCK Tsikas)

Ahead of his visit, Mr Albanese said the treaty would be a “very significant upgrade” in Australia’s defence relationship with Papua New Guinea.

“It provides for mutual defence, which means that we will provide support for each other,” he told the ABC.

“It provides for an integration of our interoperability of our assets and our respective defence forces.”

The pact will see the two nations conduct joint military exercises every year, called Pukpuk exercises, and it includes collaboration around cyberspace and electromagnetic warfare, the copy seen by the ABC says.

It says the treaty will be implemented with respect for the sovereignty, independence and territorial integrity of each other and commitment to act in accordance with the principles of international law.

A woman takes a picture of a group of females dressed in traditional attire who are posing in front of a battleship

Traditional dancers pose in front of an Australian warship docked in Port Moresby Harbour. (ABC News: Lincoln Rothall)

Former commanders raise concerns about treaty

But plans to “totally integrate” the Australian and PNG defence forces could face major legal and political hurdles in PNG, two former military commanders have warned.

Commodore Peter Ilau, who was the PNG Defence Force commander from October 2001 to January 2010, raised concerns about the implications for PNG’s sovereignty.

“The most important question here is, who takes ownership of the Papua New Guinea Defence Force?” he said.

“Loyalty number one must be to Papua New Guinea. If that is guaranteed, then by all means sign a treaty.”

A Papua New Guinean man look solemn with his arms crossed, looking at the camera.

Peter Ilau says the treaty risks being unconstitutional. (ABC News: Lincoln Rothall)

PNG has a foreign policy of non-alignment, pledging to be “friends to all and enemies to none”.

But Commodore Ilau said the pact appeared to depart from that policy, calling it a “knee jerk” reaction that could affect investment into Papua New Guinea.

“We’re putting all our eggs in one basket,” he said.

“China and Japan are heavily investing in this country. If we realign ourselves now, we are risking all the investment that’s keeping this country afloat.”

An older Papua New Guinean man, wearing glasses, looks into the camera.

Jerry Singirok wants greater consultation around the treaty. (ABC News: Lincoln Rothall)

Jerry Singirok, a former commander of the PNG Defence Force, said Papua New Guinea should protect its independence.

“I think we’ve been blinded by the fact that Australia is seeing China as a threat,” Commander Singirok said.

China’s Minister of Ecology and Environment Huang Runqiu held a bilateral meeting with Mr Marape in Port Moresby today.

When asked by the ABC about the Australia-PNG treaty, he said the question was not related to the Chinese delegation’s visit.

What do we know about the PNG-Australia Bilateral Defence Treaty?It will allow the ADF to recruit soldiers from Papua New Guinea and vice versaPNG citizens will have a pathway to gain Australian citizenship via serving in the ADFOne minister says it will “totally integrate” the two countries’ militaries and involve sharing resourcesIt says “each party recognises that an armed attack on either of the parties within the Pacific would be dangerous to each other’s peace and security and the security of the Pacific, and declares that it would act to meet the common danger, in accordance with its constitutional processes”The pact will see PNG and Australia conduct joint military exercises every year, called Pukpuk exercises