Ships in Pearl Harbor for the Rim of the Pacific exercise are preparing to make their way out to sea as sailors finish shore-based training sessions and wrap up the harbor phase of the biennial war game.

RIMPAC 2022 is the largest iteration of what has become the largest recurring naval exercise in the world. Twenty-six countries are participating in this year’s exercise, which is hosted by the U.S. Navy’s Hawaii-based Pacific Fleet. In total, 38 ships are set to take part in a series of maneuvers as they practice anti- submarine warfare, amphibious combat, humanitarian relief operations and a variety of other military maneuvers.

The ambitious exercise also comes as the Navy rethinks its fueling strategy in the Pacific after fuel from its strategic reserve at the underground Red Hill storage facility tainted its water system, which serves 93,000 Oahu residents. U.S. Defense Secretary Lloyd Austin ordered the facility’s permanent shutdown in March, and the Navy has drawn up plans for the complicated and costly defueling process.

“We have absolutely operated seamlessly without the use of Red Hill during this time,” said Pacific Fleet commander Adm. Samuel Paparo at a news conference Friday. He emphasized that Red Hill is a storage facility for fuel rather than a fueling facility and that the freeze in its operations as the Navy inches toward defueling would not affect operations.

The fuel reserve at Red Hill previously played a role during the exercise. During RIMPAC 2018 the facility provided over 19 million gallons of fuel to participating U.S. and foreign ships and aircraft, according to a Navy news release at the time.

Paparo insisted there is enough fuel available to conduct the mission without issue.

“At 38 ships it is about as stressing of a situation that you can be in, and we’ve operated it very effectively and very responsibly at this time,” he said. “We have all the capacity that we need between the on-island refining capability and what we bring in tankers into Honolulu.”

In 2020 the rapid spread of COVID-19 resulted in a heavily scaled-down iteration of RIMPAC. The exercise was cut to two weeks, and troops were confined to ships that entered Pearl Harbor only to refuel and pick up supplies. Amphibious landing exercises were canceled, with all maneuvers taking place entirely at sea.

But for RIMPAC 2022, amphibious fighting exercises are back. South Korean Rear Adm. Sangmin An serves as the commander of RIMPAC’s amphibious task force. The South Korean military has sent its largest-ever contingent to RIMPAC, including the amphibious assault ship Marado along with marines.

“The Republic of Korea is a profound and vibrant power who are more and more contributing to the international rules-based order beyond its own waters, and it’s with tremendous gratitude that the community of nations receives that partnership,” said Paparo.

The amphibious forces include U.S. and South Korean marines as well as troops from Australia, Sri Lanka, Tonga, Malaysia, Mexico and Chile.

“We’re really looking forward to the opportunity to participate in a very large exercise that RIMPAC presents,” said Royal Australian Navy Capt. Jace Hutchison, commanding officer of the HMAS Canberra, one of the ships participating in the amphibious operations. Hutchinson said that working with so many countries in such a large-scale exercise is a rare occasion.

“We don’t often get the opportunity to do that. So participating in this exercise allows us to continue work on our interoperability with our partners,” said Hutchison.

The majority of the amphibious training will be carried out at Marine Corps Base Hawaii and at Bellows Beach in Waimanalo, but Marines also will conduct artillery training at the Pohakuloa Training Area on Hawaii island and train at the Pacific Missile Range Facility on Kauai.

“A critical part of all this training has been protection of the environment, understanding everything from sea turtles and where they might be nesting and trying to lay eggs, to birds that might be nesting as well,” said Maj. Christopher Bartos, a U.S. Marine officer involved in planning the landings. “All of that is talked about across the board with every member of RIMPAC to include the partner nations that we have, so that way everybody is understanding exactly how to protect this wonderful environment that we have here while training.”

The exercise has attracted deep interest from international media. Reporters from Japan, South Korea and New Zealand are traveling with ships from their countries. Media from Taiwan also arrived in Hawaii to cover the exercise as tensions simmer in the South China Sea. Taiwanese reporters asked U.S. Navy leaders when Taiwan would be invited to the exercise.

Taiwan was absent from this year’s RIMPAC, but the possibility is open that it could participate in the future. In December, Congress passed the National Defense Authorization Act for fiscal year 2022; it included recommendations that President Joe Biden’s administration invite Taiwan to RIMPAC 2022.

While stopping short of bringing in Taiwan at RIMPAC, Biden has continued military support to Taiwan. In June the White House approved the proposed sale of $120 million in ship and ship system spare parts and related equipment to Taiwan — the fourth arms package for the island nation approved under Biden.

In a virtual meeting Thursday between the Chinese and U.S. militaries’ joint chiefs of staffs, Chinese Gen. Li Zuocheng told U.S. Army Gen. Mark Milley that China had “no room for compromise” on issues affecting its “core interests,” which include Taiwan.

“China demands the U.S. … cease reversing history, cease U.S.-Taiwan military collusion and avoid impacting China-U.S. ties and stability in the Taiwan Strait,” Li said.

Since the U.S. normalized relations with China in 1979, it has not officially diplomatically recognized Taiwan. China regards Taiwan as a rogue province, and Chinese President Xi Jinping has vowed to bring it under Beijing’s control.

However, the Taiwan Relations Act of 1979 affirmed de facto relations between the U.S. and Taiwan. The act also requires the U.S. “to provide Taiwan with arms of a defensive character” and “to maintain the capacity of the United States to resist any resort to force or other forms of coercion that would jeopardize the security, or the social or economic system, of the people on Taiwan.”

On Friday, Chinese warplanes flew into Taiwanese air space. They do so regularly, but Friday’s incursion went farther into Taiwanese territory than usual. U.S. Sen. Rick Scott of Florida was visiting at the time.

“We all have to put ourselves in a position that we can make sure we defend the freedom we all believe in,” Scott told the Reuters news service. “I do think it would be helpful if Taiwan participated in RIMPAC, and I hope that’s what happens in the future.”

Several countries participating in RIMPAC are embroiled in territorial disputes with China. Beijing considers almost the entire South China Sea to be its exclusive territory within a maritime border called the “Nine-Dash Line.” The Philippines issued a legal challenge, and in 2016 an international court ruled that most of Beijing’s maritime claims had no legal basis.

But the Chinese military has dug in, building bases on disputed land formations and sometimes attacking vessels from neighboring countries. The standoff has increasingly militarized a critical waterway through which at least a third of all global trade travels.

China previously attended RIMPAC as an invited guest in 2014 and 2016 but was disinvited in 2018 as relations between Washington and Beijing frayed.

“RIMPAC itself is not oriented against any particular nation,” said Paparo. “But it does demonstrate the solidarity of all of its participants to the international rules-based order.”