To try to halt the war in Ukraine, the U.S. and its allies have imposed the most sweeping export controls seen in decades on Russia. Now they have to enforce them.WASHINGTON — The United States, in partnership with its allies, has hit Russia with some of the most sweeping export restrictions ever imposed, barring companies across the world from sending advanced technology in order to penalize President Vladimir V. Putin for his invasion of Ukraine.The restrictions are aimed at cutting off the flow of semiconductors, aircraft components and other technologies that are crucial to Russia’s defense, maritime and aerospace industries, in a bid to cripple Mr. Putin’s ability to wage war. But the extent to which the measures hinder Russia’s abilities will depend on whether companies around the globe follow the rules.Enforcing the new restrictions poses a significant challenge as governments try to police thousands of companies. But the task could be made easier because the United States is acting in concert with so many other countries.The European Union, Japan, Australia, Canada, New Zealand, Britain and South Korea have joined the United States in imposing their own restrictions. And governments including Singapore and Taiwan, a major global producer of semiconductors, have indicated they will support the rules.“Because we have the full cooperation and alignment with so many countries, it makes enforcement a lot easier,” Gina Raimondo, the U.S. secretary of commerce, said in an interview. “Every country is going to be doing enforcement.”“That’s part of the power, if you will, of having so much collaboration,” she added.Officials from the Commerce Department, which is in charge of enforcing the U.S. rules, have already begun digging through shipping containers and detaining electronics, aircraft parts and other goods that are destined for Russia. On March 2, federal agents detained two speedboats at the Port of Charleston valued at $150,000 that were being exported to Russia, according to senior U.S. officials.To look for any potential violators, federal agents will be combing through tips from industry sources and working with Customs and Border Protection to find anomalies in export data that might point to shipments to Russia. They are also reaching out to known exporters to Russia to get them on board with the new restrictions, speaking to about 20 or 30 companies a day, U.S. officials said.Their efforts extend beyond U.S. borders. On March 3, Commerce Department officials spoke to a gathering of 300 businesspeople in Beijing about how to comply with the new restrictions. U.S. officials have also been coordinating with other governments to ensure that they are taking a tough stance on enforcement, senior U.S. officials said.Emily Kilcrease, director of the Energy, Economics and Security Program at the Center for a New American Security, said that the level of allied cooperation in forging the export controls was “completely unprecedented,” and that international coordination would have an important upside.“The allied countries will be active partners in enforcement efforts, rather than the United States attempting to enforce its own unilateral rules extraterritorially,” she said.It remains to be seen how effective the rules are in degrading Russia’s military capability or dissuading its aggression against Ukraine. But in their initial form, the broad scope of the measures looks like a victory for the multilateralism that President Biden promised to restore.Mr. Biden entered office pledging to mend ties with Europe and other allies that had been alienated by former President Donald J. Trump’s “America first” approach. A key part of the argument was that the United States could exert more pressure on countries like China when it was not acting alone.That approach has been particularly important for export controls, which experts argue can do more harm than good when imposed by only one country — a criticism that was sometimes leveled at the export controls the Trump administration issued on China.“Because we have the full cooperation and alignment with so many countries, it makes enforcement a lot easier,” Commerce Secretary Gina Raimondo said.Doug Mills/The New York TimesThe Russian invasion of Ukraine has unified Western governments like few issues before. But even with countries eager to penalize Russia, coordinating restrictions on a vast array of complex technologies among more than 30 governments was not simple. The Commerce Department held more than 50 discussions with officials from other countries between the end of January and Feb. 24, when the controls were announced, as they hashed out the details, senior U.S. officials said.Much of that effort fell to Matthew S. Borman, a three-decade employee of the Commerce Department, who in late January began near-daily conversations with the European Commission and other countries.In mid-February, Mr. Borman and a senior aerospace engineer flew to Brussels for meetings with Peter Sandler, the European director general of trade, and other staff. As a “freedom convoy” protesting coronavirus restrictions attempted to roll into Brussels, they worked from early in the morning until late in the night amid reams of paper and spreadsheets of complex technological descriptions.Each country had its own byzantine regulations, and its own interests, to consider. The European Commission had to consult the European Union’s 27 member countries, especially tech powers like Germany, France, the Netherlands and Finland, on which products could be cut off. Officials debated whether to crack down on the Russian oil industry, at a time of soaring gas prices and inflation.As Russia’s neighbors, the Europeans wanted to ensure that Russia still had access to certain goods for public safety, like nuclear reactor components to avoid a Chernobyl-style meltdown. At least one country insisted that auto exports to Russia should continue, a senior administration official said.The breakthrough came when American officials offered a compromise. The Biden administration planned to issue a rule that would bar companies anywhere around the world from exporting certain products to Russia if they were made using American technology. But those measures would not apply in countries that joined the United States and Europe in issuing their own technological restrictions on Russia.In an interview, Mr. Borman said that American allies had historically been concerned with the extraterritorial reach of U.S. export controls, and that the exclusions for countries that imposed their own rules “was really the key piece.”The Russia-Ukraine War and the Global EconomyCard 1 of 6Rising concerns. More