U.S. allies could play key roles in a U.S.-China war over Taiwan

• The U.S. has no formal commitment to defend Taiwan, but President Biden has repeatedly said that Washington would intervene.
• A Taiwan crisis could take several forms short of all-out invasion — a blockade, cyberwarfare, or attacks on offshore islands. In any contingency, U.S. allies in the region would play a critical role.

The Philippines

Driving the news: Philippines President Bongbong Marcos visited the White House on Monday, shortly after the largest-ever version of annual U.S.-Philippines military drills. For the first time, the wargames focused in part on securing the 7o-mile wide channel between the Philippines' northern islands and Taiwan.

• As U.S. and Filipino forces rehearsed for potential conflict with China, Chinese Foreign Minister Qin Gang visited Manila and urged the Philippines — a U.S. treaty ally that moved closer to Beijing under Marcos' predecessor, Rodrigo Duterte — against "picking sides."

Earlier this year, Marcos granted the U.S. access to four new bases, three of which are in the north and face Taiwan.

• Beijing's ambassador to Manila, Huang Xilian, declared in April that Washington clearly planned to use the bases to "interfere in the situation across the Taiwan Strait." Huang accused the Philippines of "stoking the fire" rather than prioritizing the security of its 150,000 overseas workers in Taiwan — comments some interpreted as a veiled threat.
• Ahead of his visit, Marcos said the bases were for collective defense not "offensive operations," and his country will not become a military "staging post."
• Asked whether the U.S. could utilize the bases in the event of war with China, a senior U.S. official told reporters Sunday, "we're careful not to go through scenarios in public."

Between the lines: The Philippines' location would make it highly significant in any Taiwan crisis.

• "At the end of that day it's about access," says Eddie Paruchabutr, an Atlantic Council fellow and former U.S. Army strategic planner who served in the Philippines. "Without the Philippines, we'd have a lot less options."
• U.S. forces could be left "floating around in the ocean" and vulnerable to Chinese missiles without access to airfields and ports in the Philippines, he says.

Japan

U.S. military facilities in Okinawa have served as staging grounds for U.S. operations from Vietnam to Afghanistan, and would likely play a central role in any Taiwan crisis — making Japan complicit from Beijing's perspective even if it took no other action.

• But Tokyo is making its own plans. In addition to stepping up cooperation with Washington, Japan is also undertaking its biggest defense spending hike in decades.

Japan is widely seen by analysts as the most likely U.S. ally to contribute troops to defend Taiwan.

• Japan's constitution limits its highly advanced military to self-defense, but some in Tokyo argue that an invasion of Taiwan would cross the threshold of endangering Japan’s survival.
• While Japan is unlikely to explicitly commit to defending Taiwan, "there are ways to signal to Beijing that it can't assume Japan would remain on the sidelines," says David Sacks, a research fellow at the Council on Foreign Relations. Those include improving command and control systems and interoperability with the U.S. forces, he says.
• In a statement, Japan's embassy in Washington said, “peace and stability across the Taiwan Strait are important not only for the security of Japan, but also for the stability of the international community as a whole."

Australia

Australia's geography would also make it a critical hub from which the U.S. could resupply its forces and launch operations.

• "The role for Australia in a Taiwan contingency is highly unlikely to be at the front line in the Taiwan Strait," says Ashley Townshend, a senior fellow with the Carnegie Endowment based in Sydney.
• But Canberra is deepening military ties with Washington and recently announced major investments in upgrading its northern military bases and in procuring nuclear submarines under the AUKUS framework.
• In a Taiwan crisis, Australia would likely be responsible for securing sea lanes and tracking Chinese vessels across a wide geographic area, and might take on tasks like escorting U.S. bombers en route to the Taiwan Strait, Townshend says.

South Korea

South Korea has also increased its military spending and cooperation with the U.S., and Korean officials have held discussions with the Pentagon about Taiwan-related contingencies. Still, Seoul's overwhelming focus remains on North Korea.

• Partially for that reason, South Korea would be unlikely to consider sending troops into the Taiwan Strait. But the U.S. could pull some of its own 30,000-strong contingent out of Korea, and would likely expect Seoul to play a key support role.
• That could leave Seoul exposed to retaliation from China, and more vulnerable to North Korea.
• State of play: South Korean officials have tended in the past to tiptoe around the Taiwan issue, but President Yoon Suk-yeoul sparked anger from Beijing last month by saying Taiwan's security was "not simply an issue between China and Taiwan" but a "global issue," like North Korea.

Then there’s Europe.

• The U.K. and France have naval presences in the Pacific, though neither has committed to defending Taiwan.
• A French official told Axios they expect the U.S. would be more focused on how Europe could hit China economically in the event of a Taiwan crisis. China-EU trade was worth $732 billion last year.
• Macron, meanwhile, argues that U.S. hawkishness risks bringing a Taiwan crisis closer — a concern other allies share ahead of the 2024 election.

The bottom line: “We’re all worried,” Townshend says of the intersection between U.S. politics and Taiwan escalation. “The whole region.”

The embassies of Australia, the Philippines and South Korea in Washington did not respond to requests for comment.