Tehran announced Monday it had breached the uranium-enrichment limits of the 2015 nuclear deal, the Joint Comprehensive Plan of Action, a week after shooting down a U.S. drone. What prompted Iran’s new aggressiveness, and what does it seek to achieve? Its policy combines two components: noncompliance with aspects of the JCPOA and so-called gray-zone activities, such as unconventional attacks through proxies, sabotage of tankers and oil pipelines, and the attack on the drone. The common view is that Iran’s goal is to pressure the U.S. to relieve economic sanctions. While this view is not entirely wrong, it misses Tehran’s most urgent priority.

Ayatollah Ali Khamenei, the supreme leader, is provoking a crisis to imbue European leaders with fear of war and economic disruption so that they will lobby the U.S. to give Iran what it wants. Mr. Khamenei timed the pressure campaign so that the European lobbying would begin at the Group of 20 summit in Osaka, Japan, last weekend. Specifically, Mr. Khamenei wants seven waivers by Aug. 1. They pertain not to banking and the sale of oil—that is, economic sanctions—but instead to Iran’s international partnerships at its nuclear sites.

The JCPOA gave Iran two big concessions: economic sanctions relief and an international blessing for its “peaceful” nuclear program. Last November the U.S. Treasury fulfilled President Trump’s order to end the JCPOA by taking away Iran’s economic sanctions relief. But the State Department, in response to European lobbying, issued seven waivers whose purpose was to support international partnerships on the nuclear projects generated by the JCPOA.

These partnerships include, to give one example, a Russian-led initiative to help produce stable isotopes, ostensibly for medical purposes, inside the Fordow facility. A fortified bunker under a mountain, Fordow’s original purpose was to camouflage and protect centrifuges that would produce weapons-grade uranium. The Russian partnership preserves the facility so it can later be used in the production of nuclear weapons.

On May 3, 2019, the State Department revoked two of the seven waivers, pertaining to the export of enriched uranium to Russia and heavy water to Oman. It was that action, not the tightening of economic sanctions in April, that led Iran to adopt an aggressive strategy.