A U.S. Coast Guard cutter crossing the Tasman Sea as part of maritime security cooperation with Australia and New Zealand knew Chinese naval ships were in the area but had no interaction with them, its commanding officer said on Tuesday.
China's navy held live-fire exercises on Friday and Saturday in international waters between Australia and New Zealand that Australian officials have described as unprecedented. The drills forced airlines to change the paths of 49 commercial flights for safety reasons.
The movements of the People's Liberation Army Navy frigate, cruiser and refueling vessel involved are being monitored by Australian and New Zealand defence forces.
The U.S. Coast Guard national security cutter Midgett arrived in port in Sydney on Saturday from New Zealand.
"We were aware of their presence," Captain Matthew Rooney, commanding officer of the Midgett, told reporters in Sydney of the Chinese ships on Tuesday.
"It did not affect our operations. We follow international norms, regulations for preventing collisions at sea and we had no encounters and we would expect the Chinese navy to do the same," he added.
Euan Graham, senior analyst with the Australian Strategic Policy Institute, said it was the furthest south the Chinese navy had held exercises, and showed China did not need a naval base in the South Pacific to project power.
China was likely testing the diplomatic resolve of Australia, New Zealand and Australia's security ally the United States, he said.
"This is a clear signal that China doesn't feel deterred from operating close by (the U.S.'s) closest Pacific ally," he said.
A spokesperson for China's foreign ministry said on Friday the People's Liberation Army Navy had been conducting exercises and training in distant waters and upheld safety standards in accordance with international laws and practices.
The U.S. Coast Guard has increased operations in the South Pacific since 2024, patrolling for illegal fishing by distant fleets including from China, at the invitation of Pacific Island countries.
China registered dozens of coast guard vessels for fisheries patrols in the Pacific Islands for the first time in 2025, although none have deployed yet.
China uses its coast guard to enforce its maritime border claims in the South China Sea.
Rooney said the U.S. Coast Guard was in the Pacific to "assist nations in maintaining their national sovereignty through bilateral invitations - bilateral maritime agreements to support operations within their exclusive economic zone to prevent malign behaviours, and also to prevent poaching of marine resources".
The commanding officer for the HMAS Kuttabul fleet base in Sydney, Captain Rebecca Levitt , said Australia has "a very large patch of ocean that we need to protect and provide that stability within the region and we can't do that without the United States".
The Midgett will next travel to Papua New Guinea on an illegal fishing patrol.
