A top American admiral has criticised a potential security pact between China and Solomon Islands, describing it as a "secret" arrangement worrying the US and its partners.
Australia has warned that a Chinese naval base in the Pacific nation, less than 2,000 kilometres from the Queensland coast, would "change the calculus" for the Australian Defence Force.
Those sentiments have now been backed by the Commander of the US Pacific Fleet, Admiral Samuel J Paparo, who said he was "undoubtedly concerned" about the situation.
"There is still a path ahead. But anytime that a secret security arrangement makes its way into the light of day, it is a concern," he told the ABC in Washington DC, during an event with foreign journalists.
"And it's a concern for all of our partners throughout the western Pacific and notably, Australia, New Zealand.
Last week Solomon Islands Prime Minister Manasseh Sogavare lashed out at critics of the draft Chinese security saying their comments were "insulting".
Mr Sogavare said the deal was "ready to be signed" but insisted existing security arrangements with Australia would be maintained and there were no plans to allow a Chinese military base.
Papua New Guinea's Prime Minister James Marape has also weighed into the controversy over the security agreement.
Australia has been trying to rally Pacific Island states to press Solomon Islands over the pact, with Scott Morrison ringing regional heavyweights including Mr Marape and Fiji's Prime Minister Frank Bainimarama to express concern.
Mr Marape told the ABC that PNG and other Pacific states were "conscious of what's taking place" in Solomon Islands, and he had had "conversations" with his Solomon Islands counterpart.
He said Mr Sogavare assured him there were no plans for China to establish a military base in the country, and that the agreement was focused on offering police support.
But Mr Marape also suggested that Papua New Guinea and other Pacific countries were in the best position to provide police support, saying "we stand ready to work side by side in upskilling and training police [and] having more police engagements ... into Solomon Islands if they require help".
Australian and Papuan police are already in Honiara as part of a regional police mission to help stabilise the country in the wake of the riots last year.
Potential Indo-Pacific conflict within 'a couple of years'
Admiral Paparo backed warnings from Defence Minister Peter Dutton of a growing potential for armed conflict in the Indo-Pacific region that Australians needed to be "realistic" about.
"I always operate under the notion that there's the potential of conflict within our region within a couple of years because of the incredible unpredictability of events," Admiral Paparo said.
"And who last year could have predicted where Eastern Europe would be right now. In fact, that is our mission, is to always be ready as militaries."
Admiral Paparo described the AUKUS arrangement, under which Australia will obtain nuclear-powered submarines through a deal with the US and the UK, as a "tangible sign" of rising tensions in the region.
He also warned that China would be watching Russia's invasion of Ukraine in the context of its own claims over Taiwan.
"Undoubtedly, the PRC (People's Republic of China) is watching what's happened in Ukraine and taking notes and learning from it," he said.
"And there will be learning and there will be adjustments to the extent that they're able to learn from it.
"And they will improve their capabilities based on what they learn at this time."
In Sydney, Defence Minister Peter Dutton has again emphasised growing military risks in the region, while announcing details of a new multi-billion-dollar missiles package.
"And when we look at what has happened in Ukraine, there is the prospect of Russia going into Poland or somewhere else in Europe, and that would be a repeat of the 1930s, and that's not something that we should allow to happen."
Mr Dutton confirmed the federal government would fast track the purchase of US-made joint air-to-surface standoff missiles for Australia's Super Hornets, and Norwegian Naval Strike Missiles for warships.
US Defence giants Raytheon and Lockheed Martin have also been announced as leading the $1 billion sovereign guided weapons program, with the aim of eventually producing missiles domestically.
