Iranian Foreign Minister Hossein Amir-Abdollahian will visit China on Friday to deepen the “comprehensive strategic partnership” the two countries signed last year. Growing Sino-Iranian security cooperation represents a serious threat to core U.S., Israeli, and Gulf Arab security interests. To address them, the Biden administration needs to take several urgent steps now.

Chinese foreign ministry spokesperson Wang Wenbin confirmed Tuesday that Amir-Abdollahian will visit China on Friday, reiterating that “China is ready to work with Iran to further deepen the China-Iran comprehensive strategic partnership.”

The 25-year strategic partnership, which Beijing and Tehran signed in March 2021, offers major benefits for two U.S. adversaries united in their opposition to the United States and to the rule of law. By building relations with Iran, China strengthens its foothold in the Middle East, undermines the United States, and further secures access to Iranian oil and other important commodities. For its part, Iran will get billions of dollars in Chinese energy and infrastructure investment, undercutting the effectiveness of U.S. sanctions against the regime.

Much of Beijing and Tehran’s cooperation focuses on economic and diplomatic ties. Indeed, the Chinese- and Russian-led Shanghai Cooperation Organization decided unanimously last September to elevate Iran to full membership.

It would be a mistake, however, to miss the security implications of the Sino-Iranian relationship.

For one thing, China’s purchase of Iranian energy and willingness to invest in Iran will have at least two negative security impacts that will get worse with time. First, Chinese investment will provide economic stimulus and revenue for Iran. If past is prologue, Tehran will use a significant portion of that additional revenue to build its missile and drone arsenal, advance its nuclear program, export terrorism, and attack its neighbors.

More broadly, additional Chinese investment will increasingly mitigate the effectiveness of U.S. sanctions against Iran. That will have the effect of intensifying Iranian intransigence in any negotiations regarding its nuclear program. China’s backing also increases the chances that diplomacy will fail and U.S. and/or Israeli military action may be required to prevent Iran from acquiring nuclear weapons.

Furthermore, while the final terms of the strategic partnership agreement remain secret, a leaked copy of the agreement, labeled “final version,” called for China and Iran to conduct combined military training, exercises, weapons development, and intelligence sharing. That should make the United States, Israel, Saudi Arabia, and the United Arab Emirates sit up and take note.

Increased Sino-Iranian military cooperation could, over time, significantly improve Iranian military capability. If Iranian forces were to acquire improved anti-access/area-denial capabilities from China, Tehran may come to believe it could deter or defend against an attack designed to halt an Iranian sprint to a nuclear weapons capability. That perception in Tehran could make an Iranian nuclear breakout both more likely and more difficult to stop.

To be clear, Sino-Iranian military cooperation is not a theoretical or future concern—it is already happening. Iran, China, and Russia conducted combined military exercises in the Indian Ocean in December 2019 and in Russia in September 2020. Another combined military exercise involving Iranian and Chinese forces is reportedly scheduled to take place in the Persian Gulf.

Notably, according to a report by the U.S.-China Economic and Security Review Commission, at least one of the ballistic missiles Iran claimed to have used in the 2020 attack on U.S. forces at Ain al-Asad Air Base in Iraq was “very likely to have been developed with Chinese ballistic missile technology.”

It’s no coincidence that the precise details of Sino-Iranian security cooperation remain opaque. Beijing has good reason to downplay the growing cooperation with Tehran. The Chinese Communist Party is eager to build relations with Gulf Arab governments, and helping the Iranian military is unlikely to win Beijing any fans in Riyadh or Abu Dhabi.

This balancing act likely explains why the foreign ministers of Saudi Arabia, Kuwait, Oman, and Bahrain—joined by the Gulf Cooperation Council’s secretary-general—are in China this week as well. Beijing is trying to cultivate relations with both Tehran and Gulf states simultaneously. That makes it necessary for China to frame its growing bilateral security cooperation with Iran in a way that will not agitate leaders on the other side of the Gulf.

That will be a challenge for Beijing, and Washington should seek to make that challenge even more difficult.

To do so, the first step for Washington is to understand that a refusal to provide Gulf Arab partners with the means to defend themselves will only incentivize them to turn to China and Russia for weapons. That would empower the United States’ two main adversaries and reduce U.S. leverage in the Middle East. This dynamic has already played out with respect to Egypt. When Cairo was unable to acquire U.S. aircraft, tanks, and missiles around 2013, it turned to Moscow and Paris for warplanes and Beijing for drones. The same dynamic is starting to play out with Saudi Arabia, and China is eager to take advantage.

Second, Washington should encourage Gulf partners to make clear to China and Russia that providing major weapons systems to Iran would seriously damage their relations with Gulf Cooperation Council countries.

Third, Congress should ensure that the Pentagon and intelligence community provide detailed, annual, written, and unclassified reports on Sino-Iranian military training, exercises, weapons development, and intelligence sharing. Statutory requirements to report on the relationship already exist but could be improved and better enforced. To inform decisions and avoid strategic surprise, Washington should proactively exchange intelligence on Sino-Iranian military cooperation with Israel and Gulf Arab partners.

The Sino-Iranian “comprehensive strategic partnership,” Iranian accession to the Shanghai Cooperation Organization, and the Iranian foreign minister’s trip to China this week demonstrate three things: a growing alignment between Beijing and Tehran, Beijing’s burgeoning clout in the Middle East, and the reality that Washington’s great-power competition with China won’t occur in the Indo-Pacific alone.

Washington may be tired of the Middle East, but Beijing is just getting started.

Ryan Brobst, a research analyst at the Foundation for Defense of Democracies, contributed to this article.