U.S Secretary of State Antony Blinken travels to Fiji on Saturday to reassure Pacific island leaders that Washington and its allies are committed to providing security and COVID vaccines, as China steps up its aid and influence in the region.

Blinken’s Fiji visit, the first by a secretary of state in four decades, follows a meeting that will take place in Melbourne of the Quad grouping of the United States, Japan, India and Australia.

“The Quad is becoming a powerful mechanism for delivering, helping to vaccinate a big part of the world, getting a lot of vaccines out there,” Blinken said en route to Melbourne. It would also strengthen maritime security to “push back against aggression and coercion in the Indo-Pacific region,” he added.

The 18 Pacific island leaders invited to the video meeting with Blinken are practiced at balancing the rival attentions of China and the United States and its allies.

The Federated States of Micronesia (FSM) said its president David Panuelo will raise climate change and illegal fishing as priorities with Blinken.

“It is plausible that the U.S and its allies have seen China’s increased presence in the Indo-Pacific as a call for more engagement in the region,” said Richard Clark, Panuelo’s press secretary.

In recent years, Beijing has upped its military and police links, while providing loans and infrastructure to Pacific island nations.

A joint statement issued by Beijing following a foreign minister-level meeting of Pacific island nations in October pledged cooperation with China’s signature infrastructure policy, the Belt and Road Initiative (BRI).

Beijing is using economic activity associated with the BRI to achieve geopolitical goals, said Peter Connolly, a former army officer and doctoral candidate at the Australian National University studying Chinese statecraft in the Pacific.

“The Melanesian states saw the BRI as a source of much-needed finance and infrastructure, but Melanesians are increasingly aware of what this has cost them, and what it could cost them in the future,” he told Reuters by email, referring to south-west Pacific nations which don’t have defence compacts with the United States.

Australian National University research fellow Graeme Smith, who studies China’s activity in the Pacific, said there was anxiety in Canberra over the potential for China to establish a military base in the Pacific.

China sent police trainers and riot equipment to the Solomon Islands in December after riots there, a first.

That “spooked” Australia, which had earlier sent police to the Solomons under a decades-old security agreement, said Smith.

Regional hub Fiji was the first Pacific island nation to diplomatically recognise China, 47 years ago, and has received hundreds of military and police vehicles from Beijing since 2018.

Fiji Prime Minister Frank Bainimarama came to power in a military coup in 2006, and U.S sanctions were only lifted in 2014 after democratic elections.

Bainimarama has been recovering from heart surgery in Australia, and although U.S officials said he is scheduled to meet Blinken, Fiji hasn’t commented on whether he has returned to Suva.

“The American people and their leaders belong at the heart of our Blue Pacific neighbourhood,” the Fiji government said in a statement this week on this visit.

The U.S State Department said defence coordination with Australia and other allies was displayed in the swift aid response to tsunami-hit Tonga last month.

Two Chinese navy aid ships are currently en route to Tonga, which became heavily indebted to Chinese companies when its capital was rebuilt in 2006 after riots.

“China’s presence in the region has certainly spurred more interest,” said Jonathan Pryke, director of the Pacific Islands programme at the Sydney-based Lowy Institute think-tank.

As Kiribati and the Solomon Islands, which switched diplomatic recognition from Taiwan to Beijing in 2019, experience a surge in COVID-19 cases this year, Australian defence planes have arrived with vaccines and emergency medical teams.

Quad nations had already delivered 485 million vaccines doses around the Indo-Pacific, Australia’s Foreign Minister Marise Payne said on Wednesday.