Early this year, Ukrainian officials came to President Volodymyr Zelensky with a risky new plan to end the war with Russia. It would require expanding their bombing campaign to include a set of targets and a class of weapons they had long avoided. In addition to Ukraine’s ongoing strikes against Russian military bases, oil refineries, supply lines, and logistics hubs, the officials wanted to launch waves of AI-enabled drones at Moscow’s airports, hoping to stop international carriers from flying in and out of the Russian capital, according to two sources with direct knowledge of the plan, which has not been previously reported.Both people spoke on the condition of anonymity to describe sensitive military operations. If executed, the plan would mark a terrifying milestone in the history of warfare: an attack in which swarms of autonomous drones equipped with AI guidance systems would seek out and hit their targets without a human pilot controlling their movements. Such systems have been tested by various countries in recent years, including the United States. But the legality of their use has been vigorously debated as a possible violation of the laws of war, and they have never been deployed at scale.When officials presented the plan to Zelensky this winter, he expressed strong reservations, one of the sources said. He worried that it could be seen as “piracy” if the drones hit a civilian airliner in Moscow, especially if the strikes killed or injured passengers, airport staff, or members of the flight crew. But in his desperation to find a Russian pressure point that could restart the peace process, Zelensky allowed preparations for the strikes to continue for several months this spring and early summer, both sources said.A spokesperson for Zelensky declined to comment. Another official in the president’s office denied the existence of a plan to launch swarms of AI-enabled drones at Moscow’s airports. “That’s total nonsense,” the official told me, asking not to be named in an article about this topic. Ukraine has long sought to force the closure of Russian airports, the official added, and its drone strikes against various targets in Russia have often achieved that goal for short periods of time. But Ukraine does not have long-range weapons that are precise and reliable enough to hit Russian airports without posing an undue risk to civilians, the official said.[Read: Inside the feud over Ukraine’s drone success]According to Russian aviation authorities, airports across the country were forced to close 114 times during a one-month period last summer, from June 28 to July 28, usually due to the threat of Ukrainian drones. Moscow was affected by the highest number of shutdowns—at least 17 in total at its four main airports. The Russian association of travel agents reported more than 290 of these incidents nationwide in the first quarter of this year. The airport closures, which Russians refer to as a kovyor, meaning “carpet,” usually last a few hours before authorities give the all-clear and allow flights to resume. “We’ve only ever had one operation against the airports,” the official said. “Force the Russians to declare ‘carpets’ all the time.”By the middle of spring, the plan to force a more permanent shutdown of Moscow’s airports had advanced far enough to receive a code name: M&Ms, a reference to the many small, cheap, and nearly identical drones that the mission would require. To overwhelm Russian air defenses, the operation would need to send as many as 1,000 drones a night to airports in and around Moscow, said one of the sources familiar with it.Attacks of that size would not be far outside the norm in this conflict. Earlier this week, Russian authorities reported shooting down 791 Ukrainian drones in a single night, one of the largest attacks of the war; more than 600 of them were flying toward the Moscow region, according to the city’s mayor.“The idea is to shut down the Moscow airspace to civilian flights for an extended period of time,” one of the sources familiar with the plan told me. Since the start of the Russian invasion, in February 2022, civilian air travel over Ukraine has been suspended. But Russian airports have mostly remained open, and millions of passengers used them this year to travel abroad. Due to Western sanctions, only a few international carriers still fly in and out of Moscow, including Turkish Airlines and Emirates, which many well-to-do Russians use to reach hubs in Istanbul and Dubai.Forcing those carriers to stop flying to Russia would make life less comfortable for officials, oligarchs, and other wealthy loyalists of President Vladimir Putin. “People in the elites might come to Putin and say: We have a problem here,” said one of the sources familiar with the Ukrainian plan. That kind of pressure from the elites, in combination with other wartime strains on Russia’s economy and society, could force Putin to negotiate a peace deal, the source said.Both sources told me planning for the operation was halted in July, when Zelensky abruptly fired its mastermind, Defense Minister Mykhailo Fedorov. As the architect of Ukraine’s military drone program, Fedorov had worked on the plan for most of this year, keeping it a secret even from some of his closest aides. He helped assemble a team of Ukrainian computer programmers to develop the AI guidance system, and he secured financing from Ukraine’s allies in Europe to produce the autonomous drones at scale, the two sources said.Having served throughout the war as a crucial member of Zelensky’s team, Fedorov changed this month into a potential rival for the presidency. In a video address posted on YouTube yesterday, the former defense minister called for Ukraine to hold elections and choose a new government. Ukraine has not held presidential or parliamentary elections since 2019, because Ukrainian martial law, which has been in effect since the start of the invasion, prohibits elections in a time of war. Opinion polls taken in recent weeks show that Fedorov has grown popular enough in Ukraine since his dismissal to pose a serious challenge to Zelensky in a presidential race. “Democracy cannot be held hostage by Russia,” Fedorov said in his speech.The same day, the Ukrainian Parliament confirmed the nomination of a new defense minister, Yevhenii Khmara, a decorated military veteran. The vote in Parliament foreclosed Fedorov’s hopes of returning to his previous post anytime soon. It also threw into doubt the future of the operation known as M&Ms. One of the sources familiar with the plan expressed hope that the new defense minister would carry it forward. “We will try. Technically it’s possible,” the source said. “You can revive this project with a new team, but it would take, in my view, around three months.” By that time, another brutal winter of war will have arrived.In the months before his dismissal, Fedorov pursued numerous high-tech plans to force the Russians to negotiate before the onset of winter. The Atlantic reported earlier this month that he had appealed for help from Elon Musk, and that Zelensky had asked President Trump to secure Musk’s assistance. The Ukrainians needed Musk to allow the use of Starlink, his satellite-communications network, as a navigation tool for drones to hit targets inside Russia, including Russian ballistic-missile launchers, with precision. Musk has refused to allow the use of Starlink over Russian territory. He has not replied to my messages seeking comment on the matter.As an alternative to Starlink, the Ukrainians have rushed to develop reliable drones equipped with AI, which offer a way to get around Russia’s counter-drone defenses. Most attack drones require a pilot to guide them to their targets, through radio signals, mobile internet connections, or some other means of remote control. Russia, like most advanced military powers, uses electronic jamming to disrupt the signal between enemy drones and their pilots, forcing the weapons to crash or veer off course.[Read: Ukraine’s plan to unnerve Putin]Last summer, the Ukrainians found an ingenious way around this problem. They hid 117 drones inside five long-haul trucks and hired unwitting drivers to bring them close to Russian air bases. Once in position, the drones connected to the internet, reportedly using Russian SIM cards, and flew out of the trucks’ secret compartments. Drone pilots back in Ukraine used the internet connection to guide most of the weapons to their targets. The mission, known as Operation Spider’s Web, damaged or destroyed roughly two dozen Russian warplanes, including nuclear-capable bombers, that stood parked on the tarmac of their bases in Russia.Ukraine’s latest plan would allow the drones to pilot themselves, using an AI-powered technique known as map matching, the two sources familiar with the plan told me. The technique involves uploading detailed maps of a drone’s intended flight path to its onboard computer, along with pictures of its targets. As the drone flies, its camera collects images of the terrain below. The onboard computer uses an AI model to compare those images with the ones stored in its memory, a bit like a person consulting a map on an unfamiliar highway. When the camera spots something that matches, or resembles, the image of the target, the drone flies into it and explodes. A human pilot does not need to confirm that the drone has found the right target before it strikes.When this technology first appeared in Ukraine a couple of years ago, some drone manufacturers told me, they had declined to make it available to their clients in the military, because they found it too risky. One drone maker showed me an AI-targeting system with a kind of accuracy selector, which he could slide up and down on a screen. If he chose the lower setting, it would give the drone permission to attack even if its AI model is only 30 percent certain that it sees the right target. The highest setting tells the AI to reach 90 percent certainty before it decides to strike. Even that did not seem precise enough for the manufacturer, who wondered what would happen if a child on a bicycle were to enter the frame of the drone’s camera as it locked onto its target: “Who is responsible if that kid dies?”Ukrainian officials, arms makers, and military officers have wrestled with such questions for years. Some have called for the Ukrainian Parliament or an international body such as the United Nations to develop guidelines for the use of AI targeting in warfare. No such rules exist in Ukrainian law. The U.S. and most of its allies have vague guidelines about a human needing to be “in the loop” before an AI model decides to attack. But most experts on the laws of war see such restrictions as outdated and insufficient.Zelensky raised concerns about unintended targets being struck when it came to the plan to attack Moscow’s airports, one of the sources familiar with these conversations told me. The officials behind the plan offered work-arounds, the source said. They suggested, for example, that Ukraine would warn civilian airlines to avoid Russian airports and evacuate their planes before the swarm of Ukrainian drones arrived. “If they say to themselves, You know what, it’s getting too risky. Why even continue flying there?” the source said. “That would already have quite an impact on the Russian elites. Those are their main connections to the outside world.”