Increasing Sino-American tensions are likely to complicate US efforts to constrain Iran’s nuclear program.

When US Iran envoy Rob Malley did a quick tour of key capitals prior to an important meeting of the International Atomic Energy Agency (IAEA) board of governors Sept. 13, 2021 he met the Western European signatories to the Joint Comprehensive Plan of Action (JCPOA) in Paris and traveled on to Moscow to talk with the Russians. China is the signatory that didn’t get a visit. He didn’t go to Beijing, and Beijing didn’t come to him. It’s yet another sign that increasing Sino-American tensions are likely to seriously complicate US efforts to constrain Iran’s nuclear program.

The conventional wisdom has long been that China isn’t interested in taking a prominent role in the Iran nuclear negotiations. China has allowed Russia to do the hard negotiating and the threatening, and when the time has come for a vote, China has supported whatever the Russians supported.

There are several reasons to think that this is starting to change. The first is the overall tenor of Sino-American diplomacy. When National Security Adviser Jake Sullivan and Secretary of State Antony Blinken met top Chinese diplomats in Anchorage in March, the tone was bitter and accusatory, and subsequent senior US visits to China have gone poorly. Last July, US Deputy Secretary of State Wendy Sherman had trouble securing meetings with appropriate counterparts, and climate envoy (and former secretary of state) John Kerry traveled to China in September only to be greeted by a low-level official and have his principal meetings over Zoom — just weeks after those same senior officials met in person with the Taliban leadership. China’s “Wolf Warrior” diplomacy is in clear view: China complains openly about US behavior, it mocks US decline, and it threatens the defiance of China will have consequences. The broad context for Sino-American cooperation is worsening.

The second is increasingly open Chinese violation of US sanctions on Iran. Starting under the Trump administration, and increasing under the Biden administration, China has been importing Iranian oil in open violation of US law. The Biden team saw its non-enforcement of sanctions as a quiet gesture of goodwill to both Iran and China. Iran got desperately needed cash and Iranians’ suffering diminished; meanwhile, China benefited from discounted oil. As long as nuclear negotiations were proceeding, a few barrels of oil here and there could act as a lubricant to the talks. Yet, China’s imports grew from a trickle into a flood in the spring, totaling about one million barrels per day in May. With the future of nuclear negotiations now in doubt, it is unclear whether Iran will simply pocket US goodwill, and equally unclear if China would be willing to shut down imports regardless of how much the United States implored it to do so.

The third is China’s notable absence from collective efforts by the P5+1 to move Iran back into compliance with the JCPOA. Russia has a whole host of disagreements with the Biden administration, and it has a complicated relationship with Iran that includes direct involvement in Iran’s civilian nuclear program. Yet, Russian officials are clearly concerned with the prospect of Iranian proliferation, and they have been outspoken about the need for Iranian restraint. A Russian diplomat, Mikhail Ulyanov, has taken a lead role in the Vienna-based nuclear negotiations with Iran, carrying messages back and forth between Iranian and US officials since Iran refuses to negotiate directly with the United States in the wake of the Trump administration’s unilateral abrogation of the agreement. The US absence gives Russian diplomacy added importance, and while Russia is aligned with neither side, a senior US negotiator told a closed-door session last week that he saw “Russia’s desire to play a positive role,” and described “a very cooperative approach in which they want to work with us to see whether we could get back into the deal.”

China has serious concerns about Iranian proliferation as well, but it is happy to be a free rider on global efforts to constrain Iran. China intones all of the right sentiments about the desire for a negotiated resolution to disputes, but it simultaneously pursues its own agreements with Iran, building on its overwhelming advantage due not only to the relative size of the two countries’ economies, but also Iran’s isolation in the world. China accounts for about a third of Iranian trade, and Iran accounts for less than 1 percent of Chinese trade. The Chinese economy is 30 times the size of Iran’s, and its population is 18 times as large. China is an elephant, and Iran is an ant. While China sees Iranian proliferation as undesirable, it does not feel threatened by Iran. Instead, China sees Iran as a useful instrument to use in its foreign policy, calibrating its distance and closeness to Iran in some measure as a way to draw closer or pull further from the United States and its allies. The key impulse now is to pull further.

For the United States, this comes as difficult news. The views of Iran’s leadership toward nuclear negotiations remain unclear, but there are increasing signs that the Raisi government — and the clerical establishment behind it — is more distrustful toward the United States than ever before and is resolved to hold out against a return to the JCPOA. A China that is increasingly focused on undermining demonstrations of US power and influence becomes an accessory to Iranian resistance, serving dual goals of winning special favor with Iran — which will pay economic benefits to China — and undercutting the US global position.

The Biden administration seems to understand that its reorientation toward the Pacific will have global consequences, as the current tensions with France demonstrate. But up to now, it doesn’t seem to have much of a strategy for pursuing common diplomatic interests with China while compartmentalizing bilateral tensions. Iran represents an interesting example of how the United States has managed just such a task with Russia. If the United States could manage a similar trick with China over Iran issues, that could spread to other issues such as climate. If not, it could prove enormously difficult for the United States to win a return to the JCPOA, let alone the “longer and stronger” agreement that the administration has set as its goal.

The above writer, Jon B. Alterman, is a senior vice president, holds the Zbigniew Brzezinski Chair in Global Security and Geostrategy, and is director of the Middle East Program at the Center for Strategic and International Studies in Washington, DC.