Will America’s Asian allies get dragged into the Iran war?

US President Donald Trump has a request. Having made a mess of global energy markets by attacking Iran, he is now demanding that America’s allies around the world send forces to help open the Strait of Hormuz. In a post on his social network on March 14, Mr Trump named Asian allies including Japan and South Korea among a list of foreign powers that he hopes will send ships to the Gulf.

And not just allies: “I think China should help too,” Mr Trump told the Financial Times on March 15. The next day, he sought to delay a summit, scheduled for later in March, with Mr Xi Jinping, China’s leader, so he could focus on the war.

Summit or not, Chinese help is unimaginable. Like India and Turkey, China appears to have cut a deal with Iran to keep supply lines open, including for oil.

Yet America’s five Asian allies face a much trickier dilemma. Iran’s threat to attack shipping near the Strait of Hormuz is badly disrupting energy supplies to Australia, Japan, the Philippines, South Korea and Thailand. These countries worry about their armed forces becoming embroiled in a distant conflict over which they have little control. They also fear being abandoned by America – especially if it concludes that they are not pulling their weight.

South Korea has an anti-piracy force, the Cheonghae unit, that operates in the Gulf of Aden. But redeploying this unit, or others, might require parliamentary approval. Public backlash to such ideas has already begun. “Sending South Korean warships is… nothing less than a military mobilisation supporting the war of aggression,” declared the Korean Confederation of Trade Unions. “Trump, who started the fire, charges South Korea a firefighting bill,” read a wry headline in the JoongAng, a South Korean daily.

Since the start of the war, Australia has sent a command-and-control aircraft and some air-to-air missiles to the Middle East. But it has been careful to frame its response as an effort to help defend the United Arab Emirates (home to many Australians), rather than a boost to America’s war effort.

Few Asian leaders will come under more pressure to pitch in than Ms Sanae Takaichi, Japan’s Prime Minister, who is scheduled to meet Mr Trump at the White House on March 19 as part of a trip planned before the war.

Japan has minesweepers that could help open the strait. But polling suggests 75 per cent of Japanese oppose the conflict. There are also tricky questions about Japan’s pacifist Constitution.

Laws passed in 2015 by the late Abe Shinzo, then Prime Minister, allow the government to engage in “collective self-defence” beyond its borders; minesweeping operations in the Strait of Hormuz were among the scenarios debated in Parliament at the time. When pressed by opposition leaders about whether Japan would aid America if it launched a pre-emptive strike that led to a war, Mr Abe dismissed the possibility: “Japan would not support such a country.”

Allies in Asia nevertheless may feel obliged to answer Mr Trump’s call. He has long threatened to withdraw American support for allies unless they pay tribute to Uncle Sam. Asian allies hand over billions of dollars per year to ensure American security commitments; in recent wrangles over tariffs, they have pledged to plough more than a trillion dollars into America’s economy. Now they are worrying that American forces stationed in Asia will leave for the Middle East regardless.

Already an American Marine expeditionary unit based in Japan has begun sailing towards the Gulf at high speed. The last time it departed the Pacific – leaving Asia without an American crisis-response force – was in 2004 during the war with Iraq. America has also redeployed Patriot interceptor missiles and parts of a THAAD missile defence system based in South Korea.

It is possible to overstate the significance of these movements. The expeditionary unit is of an older design – not the new-fangled sort that would be most useful in preventing a Chinese attack on Taiwan. And experts say that America can continue to deter North Korea without the THAAD system.

But the redeployments are nonetheless fuelling doubts about America’s commitment to the region. Mr Lee Jae Myung, South Korea’s President, expressed disappointment that American arms had been removed from his country. When the THAAD system was first sent to South Korea in 2017, it enraged China, which responded by encouraging consumers to boycott South Korean goods and services, causing massive economic losses. South Korea held firm, despite the costs and the THAAD system remained. Now bits of it have suddenly been whisked away. “The stark reality is that we cannot always get our way,” Mr Lee told a Cabinet meeting.

Taiwan is in perhaps the most precarious position. America is not bound by treaty to defend the island, as is the case for other Asian allies. But it has long pledged to deter a Chinese assault by selling Taiwan weapons it can use to defend itself, a commitment embedded in law. Taiwan’s government now worries that the conflict in the Middle East might delay the arrival of arms it has ordered from America – especially the kind that America and Israel need for their fight against Iran, such as Patriot missile interceptors.

In 2022, Taiwan agreed to buy around 100 PAC-3 MSE missiles (the most advanced Patriot interceptors) for delivery in 2025 and 2026. It has also ordered NASAMS interceptors and HIMARS rocket launchers. Many of these purchases aim to bolster Taiwan’s defences by 2027 – the year by which, so American officials believe, Mr Xi has ordered his armed forces to be ready to attack or blockade Taiwan. Any delay would affect Taiwan’s military planning and badly damage public morale.

All of this has Asian allies thinking about their Plan B. “If we rely on others, what will we do if they don’t come through?” South Korea’s Mr Lee asked his ministers last week. “We must always consider what we will do if, for any reason, external support were to disappear.” © 2026 THE ECONOMIST NEWSPAPER LIMITED. ALL RIGHTS RESERVED.