Scott Morrison says China building a military base on Solomon Islands would be the "red line" for Australia and the United States, but did not say how Australia would respond if it happened.
There are concerns about a recently signed security agreement between China and Solomon Islands and what it could mean for Australia and other pacific countries, especially if China uses the deal to expand its military presence to the region.
"This is a shared concern, not just Australia, this is Australia and regional governments, particularly places like Fiji and Papua New Guinea," Mr Morrison said.
"Working together with our partners in New Zealand and of course the United States, I share the same red line that the United States has when it comes to these issues.
"We won't be having Chinese military naval bases in our region on our doorstep."
Mr Morrison would not say how he would respond if re-elected, if the "red line" was crossed and China did move to establish a military base.
He instead said that Solomon Island's Prime Minister Manasseh Sogavare assured him it would not happen.
"So he clearly shares our red line," Mr Morrison said.
The government has faced sustained criticism from the opposition about the deal, with Labor arguing the Coalition should have done more to prevent it, including sending Foreign Minister Marise Payne to Solomon Islands when concerns about the pact first arose last year.
The Prime Minister and senior Labor figures were both campaigning in Alice Springs with their candidates for the seat of Lingiari.
Shadow Foreign Affairs Minister Penny Wong all but confirmed if Labor was elected it would increase the foreign aid spend in the Pacific, to secure the region.
She said there were a number of things Labor would have done differently to prevent the pact if it had been in government.
"We wouldn't have cut foreign and development assistance which is important to development and national security. We wouldn't have cut bilateral aid by 28 per cent on average every year," Senator Wong said.
"We wouldn't have mocked Pacific Island nations about water lapping at their doors which is what Peter Dutton did standing next to Scott Morrison.
"And we wouldn't have thumbed our nose at Pacific leaders when they told us at a forum that climate change was their number one national security issue.
"So yes, I do think there's a different approach. Do I think it's easy? No, I do not which is why it shouldn't be the subject of shrill scare campaigns."
On Saturday, Shadow Treasurer Jim Chalmers flagged that he believed cuts to foreign aid by the government were partly to blame for the controversial deal going ahead, "by being a credible partner on climate change, having a credible climate change policy".
In the past decade, spending on foreign aid has been slashed by a third, but Australia remains the biggest donor in the Pacific with $1.7 billion set aside for the region a year.
Solomon Islands receives about $170 million of that, but its share has fallen since the end of RAMSI — Australia's multi-year assistance mission to the nation.
Solomons sovereignty at risk, Joyce says
Deputy Prime Minister Barnaby Joyce has also warned Solomon Islands it has put its sovereignty at risk by signing a security agreement with China.
Mr Joyce said he had taken the Solomon Islands' word that it would not allow China to establish a naval base on the island, but that, if it did, it would be "obviously an intimidating tactic" for Australia.
"[China wants] to. There's no doubt about that because we see what they did in the South China Sea where they said they weren't going to militarise," he said.
"Obviously for the Solomons, I take their word but I say be really careful to invite a totalitarian power into your country because it's going to affect your sovereignty."
Mr Joyce again defended the Prime Minister and the government's attempts to engage with Solomon Islands leadership before the deal was signed.
However, he also would not say how Australia would respond if China did begin to build a military base because the country had said it would not happen.
When asked what a re-elected Liberal and Nationals Coalition would do to stop China from encroaching further into the pacific, the Deputy Prime Minister pointed to projects — such as the nuclear submarine deal, AUKUS, the Quad alliance between Australia, India, Japan and the US — as examples of things the government was doing to prevent that.
The government has faced sustained criticism from the opposition about the deal, with Labor arguing that the Coalition should have done more to prevent it, including sending Foreign Minister Marise Payne to Solomon Islands when concerns about the pact first arose last year.
