(CNN)China and Australia have found another battleground for their deepening diplomatic standoff: the Pacific Islands' pandemic response.
Canberra has hit back at Beijing's claims it is derailing the rollout of Chinese vaccines in Papua New Guinea (PNG), the most-populous Pacific nation. "We support Papua New Guinea making sovereign decisions," Australia's minister for the Pacific, Zed Seselja, said in an interview with CNN on Wednesday.
That's not the way Beijing sees it. In early July, Chinese state-run tabloid Global Times accused Australia of sabotaging China's vaccine rollout in the Pacific. At a press conference earlier this month, a spokesperson for China's Foreign Ministry slammed Australia for "undermining vaccine cooperation" in the region.
For years, the countries have jockeyed for influence in the Pacific, a region of 14 island nations and territories with a population of about 10 million people with strategic advantages for both sides.
The islands' location between US and Asia makes them key military staging grounds and the potential site of future defense installations for either Australia or China.
Australia has longstanding economic and cultural ties with the Pacific, and it is crucial to the country's national security to ensure the Chinese government doesn't gain a large foothold in the region.
For China, the region represents an opportunity to expand its influence. Several of the islands are among the last nations in the world to recognize Taipei as a diplomatic partner over Beijing. The Chinese government would like to lure them away from Taiwan as part of its long-running strategy to isolate the island.
Now all that political maneuvering has turned PNG's Covid-19 outbreak into another area of competition as Australia and China present themselves as benevolent partners.
Yet China's 300,000 vaccine donations to the Pacific have failed to meet Australia's nearly 600,000 -- and with Canberra promising to supply another 15 million doses to the region, Beijing is on the backfoot.
Is there any truth to the accusations?
PNG avoided the worst of the pandemic in 2020, but this year its cases have skyrocketed, bringing its total to more than 17,000 reported cases and 179 deaths.
When PNG's cases were starting to soar in February, China announced it would send vaccines. The shots it offered hadn't yet been approved by the World Health Organization (WHO), so China agreed to provide trial data, according to the Global Times.
Yet PNG didn't approve the vaccines until May. That delay, according to the Global Times, was due to Australian consultants "working in the shadows" in PNG to "manipulate" local policies.
"Australia has been found sabotaging and disturbing Pacific Island nations' cooperation with China on vaccines and anti-virus measures," the Global Times report claimed.
While Australia has dispatched health experts to PNG during the pandemic to strengthen government systems and provide frontline logistic support, Seselja said he wasn't aware of them giving advice on Chinese vaccine efficacy.
He also noted that Australia had been contributing a range of health care expertise to PNG long before the pandemic.
"Our commitment to the Pacific is longstanding and comprehensive," Seselja said. "Any suggestion we do it in response to other countries is not well founded if you look at decades of consistent wide-ranging support."
Joanne Wallis, a professor in international security at the University of Adelaide, said it wouldn't have been unreasonable for Australian health experts to act as consultants to provide information to PNG on the efficacy of different vaccines.
Australia's Department of Foreign Affairs and Trade and PNG's Covid-19 National Pandemic Response office did not reply to CNN's request for comment.
The reality for the delay in approving the Chinese vaccines was likely a simple case of timing.
PNG authorities said they wanted Sinopharm to get WHO approval before rolling the vaccine out. By the time that happened in May, PNG had found alternatives.
It had little choice. During March, the country of 7 million was reporting hundreds of Covid cases a day, raising fears the outbreak could overwhelm the island's already fragile health system.
That month Australia announced it would send 8,000 doses of AstraZeneca to PNG. In April, PNG received 132,000 AstraZeneca vaccines from global vaccine alliance COVAX. Australia sent another 10,000 doses in May, and New Zealand sent 146,000 in June.
Australia is able to be so generous due to an excess of AstraZeneca shots at home. After initially intending to use AstraZeneca for its entire population, the government now only advises its use for those over 60, due to the greater risk of blood clots in younger people. Extra Pfizer vaccines have been bought for under the 60s.
Jonathan Pryke, director of the Lowy Institute's Pacific Islands Program, said it was "terrible optics" that Australia wasn't rolling out AstraZeneca to everyone domestically, but was happy to give it to Pacific countries. "The silver lining of that is that (Pacific Islands) are getting much more vaccine much earlier than they otherwise would have been, if these restrictions weren't in place in Australia."
Seselja dismissed the idea that AstraZeneca was not good enough for Australians. "It is good enough -- millions of Australians are receiving it," he said.
How are Australia and China's overtures playing in PNG?
PNG has a bigger problem than a diplomatic spat on its shores -- it is struggling to get vaccines into people's arms.
As of July 4 PNG had only vaccinated about 60,000 of its 7 million people and, as of early June, 130,000 vials of AstraZeneca provided by COVAX were set to expire at the end of this month.
That's partly because there's huge vaccine hesitancy in the country, said Justine McMahon, PNG country director for humanitarian non-profit CARE International, who is based in the country.
Some health workers have refused to take it over efficacy concerns, and some mothers have missed measles vaccine appointments because they feared their babies would be given a Covid-19 shot at the same time, she said.
"If they're faced with these kinds of challenges with the vaccine supply that they've already got access to, why bother even trying to incorporate one new vaccine into the mix?" said Pryke, from the Lowy Institute.
Despite that, Australia has committed more vaccines to the region -- this month, the government announced it would roll out 15 million Covid-19 doses to Timor-Leste and Pacific nations in the next 12 months, meaning much of the adult population in the region could be vaccinated next year.
There are good reasons Australia wants to supply the region with vaccines.
Australia is separated from PNG by just a few hundred miles. Although travel is restricted between the two countries, officials fear cases will spill over the border. Australia -- which controlled PNG for decades -- also sees itself as having a responsibility to help out.
"Helping PNG is a no-brainer for Australia, and that was the case long before China even had a major presence within the country, but it's even greater with that element layered on top of all the other complex dynamics of the relationship," Pryke said.
China is one of the world's biggest vaccine donors, but in the Pacific, it doesn't have that title.
Covid-19 had been a great opportunity to build influence with not a lot of money. But during the pandemic, China has been "missing in action" and its efforts had been "tokenistic," Pryke said.
"So they've got to show that they're actually doing something," he said. "They've found themselves quite on the back foot in regards to influence-building now we're 18 months into this crisis."
So far, China has donated 270,000 vaccines to the Solomon Islands, Papua New Guinea, and Vanuatu, according to analytics company Airfinity -- less than half Australia's contribution. Chinese President Xi Jinping has also offered to provide vaccines to Fiji, TVNZ reported.
Beijing's vaccine diplomacy push in the Pacific had been "stunted," Pryke said. Although senior leaders of both Vanuatu and the Solomon Islands publicly received a dose of the Chinese vaccines, there's been little fanfare over Beijing's vaccine contributions in the region.
For now, China hasn't made any accusations about Australian influence in those countries. But as a MOFA spokesperson told CNN: "As for whether the relevant countries are under pressure from Australia in the process of approving the use of Chinese vaccines, the Australian side should know what they have said and done."
What does this mean for the Pacific?
Since last year, relations bet