Defence Minister Peter Dutton has appeared to contradict the prime minister over the threat China poses in the Solomon Islands.
Scott Morrison said Honiara had categorically ruled out a military base being established under the pact.
But Mr Dutton chastised China for “not playing by the same rules”.
“You can expect the Chinese to do all they can now that they’ve got this agreement signed,” Mr Dutton told Sky News when questioned on whether troops would move in.
“(China said) the South China Sea would not be militarised (and) today, they’re militarised. They’ve got airstrips. They’ve got fuel depots. And that’s the reality of China under President Xi.”
The government is under fire for not sending a minister to the Solomons Islands when a proposed security pact with China was made public in March.
Australia’s top defence brass and security heads didn’t advise the federal government to send a more senior minister to the Solomon Islands, Mr Dutton says.
Pacific Minister Zed Seselja was dispatched to Honiara last week in a last-ditch attempt to stop the deal from being inked.
Mr Dutton defended the government’s action, saying the response was discussed in depth during National Security Cabinet meetings.
“We have taken the advice of the chief of the Defence Force and the Department of Foreign Affairs and Trade,” he told the Seven Network.
“We’ve had those briefings and we’ve gone through what was known and what was available to us in what has been a delicate period and it was a very deliberate decision to send Zed over Marise Payne.”
Labor has criticised the government for not acting sooner, with foreign affairs spokesperson Penny Wong calling the development the greatest foreign policy failure since World War II.
“On Scott Morrison’s watch our region has become less secure and the risks that Australia faces have become much greater,” Senator Wong told the ABC.
Mr Dutton echoed the words of Mr Morrison the previous evening, accusing Labor of “taking China’s side”.
“The problem here is not Australia, the problem is China and President Xi,” he said.
But some confusion remains about what the government knew, and when.
Solomon Islands opposition leader Matthew Wale said he warned the Australian embassy in Honiara about a potential Sino-security pact in August 2021.
But the foreign affairs department has contradicted this, saying Mr Wale met with the High Commissioner in May 2021 and “officials did not discuss a possible security agreement with China during this meeting or any other”.
Foreign Minister Marise Payne and Senator Seselja said they were made aware of the security pact with China when it was leaked on social media.
But Mr Morrison on Wednesday told reporters “this is no surprise to us” when questioned on the pact.
Finance Minister and Liberal campaign spokesman Simon Birmingham refused to be drawn on what officials knew.
“I am not going to go into either the sensitivities of the intelligence briefings or confidential discussions we have with governments and other partners,” he told the ABC.
“That would be detrimental to our long term interests in engaging with other countries.”