The U.S and Micronesia have agreed to renew a key strategic pact, U.S presidential envoy Joseph Yun said, adding he hopes for similar progress with Palau, as the U.S shores up support among Pacific island nations to counter competition from China.

Yun said on Monday that the Compact of Free Association agreement (COFA) with Micronesia would be signed on 22 May at a ceremony in Papua New Guinea, attended by U.S President Joe Biden.

Washington first reached the COFA accords in the 1980s with Micronesia, Palau and the Marshall Islands. The U.S. retains responsibility for the defense of the nations and provides economic assistance, in return gaining exclusive access to huge strategic swaths of the Pacific.

Renewing the COFA agreements has become a key part of U.S efforts to push back against China’s bid to expand its influence in the Pacific.

Yun said he initialed the agreement with new Micronesian President Wesley Simina and would formally sign it with him next week in Port Moresby on the sidelines of a second summit between the United States and Pacific island leaders.

“It’s absolutely a done deal,” he said adding: “I am (now) going to go to Palau. Where I hope to make similar progress.”

Yun said he expected to be in the Marshall Islands from Thursday until Sunday, but was “doubtful” its COFA agreement could be finalised at the moment.

The old COFA provisions expire in 2023 for the Marshall Islands and Micronesia and in 2024 for Palau.

Biden will next week become the first sitting U.S. president to visit the Pacific islands state of Papua New Guinea following the G7 summit in Japan, underscoring his administration’s investment in the Pacific region to counter China.

Washington has already signed memorandums of understanding on future assistance with the three COFA states. Yun said last month the “topline” agreements with the three nations would provide them with a total of about US$6.5 billion over 20 years.

Last year, more than 100 arms-control, environmental and other activist groups urged the Biden administration to formally apologise to the Marshall Islands for the impact of massive U.S nuclear testing there and to provide fair compensation.

Marshall Islanders are still plagued by health and environmental effects of the 67 U.S nuclear bomb tests from 1946 to 1958, which included “Castle Bravo” at Bikini Atoll in 1954 – the largest U.S bomb ever detonated.