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 between the Solomons and China.
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 Solomon 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.
Labor's campaign spokesman Jason Clare attacked the government for sending Senator Seselja instead of the foreign minister.
"(US President) Joe Biden is sending Kurt Campbell, his most senior diplomat in the Pacific. We sent Zed. Who the hell is Zed Seselja?"
Mr Dutton defended the government's action, saying the response was discussed in depth during cabinet national security committee 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 spokeswoman Penny Wong calling the development the greatest foreign policy failure since World War II.
Mr Clare said the development was an "epic fail" on Mr Morrison's watch.
"The prime minister said, 'This is not a surprise'. If it's not a surprise, it makes it worse. It means he knew this was happening and he didn't act fast enough," he said.
"You've got the prime minister saying 'No big deal'. You've got his deputy (Barnaby Joyce) saying 'It's a crisis'."
Mr Clare says Labor will seek a security briefing on the matter, but dodged questions over why the party hadn't sought a briefing earlier given its attacks on the government's timeliness.
"We see regular security briefings. I would expect that we seek a briefing on this particularly given this is during the caretaker period," he said.
Former Solomons prime minister Danny Philip told an online security forum on Thursday a major motivation for signing the pact was to protect Chinese citizens, businesses and investment partly because Australian security forces could not guarantee their safety.
"A senior Australian diplomat said to us they are not here to protect Chinese interests. So that means we need to think about how to support our police force," Mr Philip said.
Solomon Islands opposition leader Matthew Wale said he warned the Australian embassy in Honiara about a potential Sino-security pact in August last year.
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.
Australian Associated Press
Sign up for our newsletter to stay up to date.