U.S. chips enable Russia’s war drones. It’s time to stanch the flow.

The Shahed- 136, a delta-winged drone with high-explosive warheads designed by Iran, is one of Russia’s more destructive weapons in the war against Ukraine, killing civilians as well as combatants. Russia is building a factory to mass produce them, with help from Iran. The two countries, both under some of the world’s heaviest sanctions, hope to build a total of 6,000 drones by the middle of 2025.

The United States should attempt to choke off the supply of integrated circuits that enable these flying killers — most of which come from the United States.

According to a detailed inventory in leaked documents, more than 90 percent of the drone’s computer chips and electrical components are manufactured in the West, primarily in the United States. Only four of the 130 electronic components in each drone are made in Russia.

The Institute for Science and International Security, which has long tracked illicit Iranian nuclear programs, found that Iran and Russia would need to procure 320,000 integrated circuits to build 5,400 additional drones. Many of the electronic circuits “appear to be readily available” from manufacturers and online marketplaces.

The Institute noted that “None of the items appear to be listed on the U.S. Commerce Control list that controls the export of listed items due to technical specification and potential for military and civilian applications.” However, the components would be covered by a near-blanket ban the United States recently imposed on the export of electronics to Russia. During the war, Russia has evaded U.S. sanctions by importing goods through third countries. A think tank, the Silverado Policy Accelerator, has identified Hong Kong, China, Kazakhstan and Armenia as major integrated circuit exporters to Russia in the first year of the war. These channels sustain Russia’s brutal destruction of Ukraine.

A redoubled effort should be made to stanch the flow of integrated circuits and other dual-use electronics to Russia. These parts might be traceable by serial and part numbers recovered from downed drones, and there are relatively few manufacturers of the more sophisticated components.

A redoubled effort could focus on blocking the flow of the highest priority items — electronic integrated circuits — by companies, their foreign subsidiaries, distributors, logistic and transportation providers, and by allied governments. To aid customs officials as well as manufacturers and distributors, Washington could identify and send out “gray lists” of suspicious companies in third countries that might be complicit in delivering these parts to Russia.

A concerted government and private sector effort could call together top managers from leading companies and distributors and press them to apply stringent internal controls over the sale of key electronics, while also flagging customers who might have been selling them to Russia.

Without U.S. chips, the dreaded Shaheds won’t be exploding over Ukrainian apartment buildings in the middle of the night.