US President Donald Trump’s decision to block ship traffic through the Strait of Hormuz presents China with a sticky choice: to accept Trump’s prohibition on trade with Iran, Beijing’s staunch ally, or challenge the closure and turn this Middle East conflict into a duel between nuclear-armed superpowers.

China had largely watched the joint US-Israeli war on Iran, now more than six weeks old, from the sidelines. It had criticized the massive bombing campaign, observed Trump’s difficulty in bending Iran to his will, while enjoying cut-rate Iranian supplies of crude oil and natural gas that freely traversed the strait into the Indian Ocean.

That scenario faces a new and dangerous moment. To maintain its fossil fuel supply and also show Iran that their alliance is worth preserving, China must challenge the American blockade. Trump says the strait will remain closed until all ships, including those of America’s Arab allies, can pass through freely.

Zineb Riboua, a Middle East expert at the Hoover Institute, a conservative US think tank, asserted that budding crisis “is all about China.”

“Beijing has spent billions of dollars building Iran into a structural asset,” Riboua wrote in a report she penned just days after Trump and his Israeli wing-man Prime Minister Benjamin Netanyahu began the aerial bombing campaign. “By striking Iran directly, the Trump administration is dismantling – whether by design or by consequence – a pillar of China’s regional architecture.”

In that context, the tough-guy reputations of Trump and China’s leader Xi Jinping are at stake. The two had already entered a kind of low-intensity World War III dance during which the United States had moved step by step to turn back what Trump considered unacceptable Chinese inroads into areas important to US security.

He first sent commandoes into Caracas, the capital of Venezuela, to nab President Nicolas Maduro and spirit him off to New York to face trial on drug trafficking charges. Maduro sold petroleum to China and in return bought military equipment.

China made no move to save Maduro. The Caribbean Sea is America’s watery southern backyard and China possessed no military hardware to contest Trump’s move. Saving Maduro seemed a risky adventure at best and hardly worth the effort: Beijing had bought only four percent of its petroleum needs from Venezuela and sold a smattering of weapons to the Latin dictatorship.  

Iran offers different value as an ally. For one thing, the percentage of fossil fuels that Iran provides China is much higher – 15 percent of the county’s annual needs, purchased at below-world-market prices.

For another, Xi had developed a deep partnership with Iran in developing the country’s rare earth mineral industry. The minerals have become a coveted resource globally due to their importance in producing high-tech computer chips. Advanced economies – including the United States – are scrambling to secure access to mines world-wide.

The chips are important to manufacturing and operation of everything from computer games to mobile phones to artificial intelligence. They are also a basic tool of modern warfare. They guide key weaponry the US uses in the Iran: war, including guidance systems for Tomahawk cruise missiles and controls of flight and weapons systems for US F-35 fighter jets and armed drones.

China produces about 90 percent of the Earth’s refined rare earth material and seems to want to control more. In 2021, Beijing agreed to provide Iran with 400 billion dollars worth of economic aid over 25 years in a deal to ensure secure access not only to oil but also to rare earth minerals.

OilPrice, an online energy news outlet, wrote that by positioning itself as a rare earth mineral “hub,” Iran increases its value to a powerful ally. This gives Xi “a reason to view the country as more than a ‘sanctioned’ gas station.”  

“The US move against the regime is a direct threat to this resource axis,” OilPrice concluded.

Beyond mineral mining, Chinese companies have been involved in building Iran’s telecommunications network. The work has encompassed modernization of Iran’s ability to monitor its domestic telephone and internet system to keep tabs on potential dissidents.

During anti-government demonstrations that broke out in January, the Iranian government used Chinese-supplied spying tools, include facial recognition cameras, to identify protestors and kill or round them up.

Iran also used China’s so-called “Great Firewall” technology to shut down the country’s entire internet services, in order to keep information about its harsh repression out of  view. “Iran has not developed its censorship infrastructure in isolation,” Washington-based Arab Gulf States Institute, a think tank, wrote in a January report.

“The regime has received assistance from China, the world’s most experienced practitioner of internet control.”  

Such systems “can track internet users, reconstruct email messages, block internet traffic, and deliver manipulated web pages. Governments have invested billions in technology designed to monitor citizens, censor content and isolate populations during periods of unrest,” AGSI noted.

All this is threatened by the American-led offensive. Gradual Chinese diplomatic successes may also come undone. China had brought together Iran and Saudi Arabia, longtime enemies, to renew their bilateral diplomatic relations. Xi had also welcomed Iran into its Shanghai Cooperation Organization, China’s regional security grouping, and had begun an extension of its Belt and Road Initiative to transport Chinese goods across the expanse of Central Asia to the Indian Ocean.

What can China do to show clients such as Iran that it is a reliable ally? Soon after the invasion, China took a legalistic approach. “The sovereignty, security, and territorial integrity of Iran and other regional countries must be respected,” Fu Cong, China’s ambassador to the United Nations. “China stands ready to work with the international community to advance peace efforts and help restore peace and stability in the Middle East at an early date.”

On Tuesday, April 14, as the US blockade of the Strait of Hormuz and Iranian ports leading to it got underway, the Chinese tone stiffened. “Chinese ships continue to move in and out of the waters of the Strait of Hormuz,” the Foreign Ministry said in a defiant statement. “We have trade and energy agreements with Iran, which we will respect and abide by. We expect others not to interfere in our affairs. Iran controls the Strait of Hormuz, and has opened it to us.”

No confrontation at sea between nuclear powers has occurred since the middle of the Cold War. In 1962, US President Jon F. Kennedy ordered a naval blockade of Cuba to keep Soviet ships from delivering nuclear-armed ballistic missiles to Cuba. A clash was averted when the Soviet ships withdrew. A secret compromise avoided war: the US pledge not to base nuclear armed missiles in Turkey, a NATO ally.

Is the Hormuz Crisis heading toward combat rather than some sort of compromise?  “Chinese support for a US adversary could directly result in American casualties,” warned Joe Webster, a geopolitical and energy expert who writes the China-Russia Report blog. “What will be the US response if Chinese military intelligence support for Iran results in the deaths of US airmen or sailors?”

It’s a good question.