At a critical strategic juncture, non-state actors threaten to complicate the conflict.

For the past four years, the U.S. has tried to nab Yevgeny Prigozhin, a dour and balding Russian oligarch often photographed somewhere close to Vladimir Putin. He’s been dubbed Putin’s chef. His companies cater Kremlin events and allegedly finance the Russian leader’s political and military escapades. In 2018, a U.S. federal court issued an arrest warrant for Prigozhin for, among other things, “conspiracy to defraud the United States.” It charged that the restaurateur turned billionaire, through his funding of the Internet Research Agency, “oversaw and approved” widespread meddling in the U.S. political system, including in the 2016 Presidential election. Last year, the F.B.I. put Prigozhin on its most-wanted list and offered a quarter of a million dollars for tips leading to his arrest. The U.S. Treasury has also sanctioned Prigozhin for running disinformation campaigns through a network of front companies in other elections in Africa, Asia, and Europe. Last month, the U.S. imposed additional sanctions on Prigozhin (along with his wife and two children). “We continue to impose very severe economic sanctions on Putin and all those folks around him,” President Biden said at the announcement.

Prigozhin is in the spotlight again this month as Putin, facing humiliating military setbacks in Ukraine, looks for ways to regroup on the battlefield. U.S. and British officials say that Russia is now scrambling to mobilize mercenaries from the notoriously opaque Wagner Group, which is reportedly financed by Prigozhin. NATO recently estimated that up to fifteen thousand Russians have been killed in just the first four weeks of the war—about the same as the Soviet Union lost during its decade-long invasion of Afghanistan. Russia is expected to redirect more than a thousand mercenaries in the Wagner Group, including senior leaders, from wars on other continents to Ukraine, the British Ministry of Defense said, last week. Because of the “largely stalled invasion,” it added, “Russia has highly likely been forced to reprioritise Wagner personnel for Ukraine at the expense of operations in Africa and Syria.”

Since Putin launched his attack, both Ukraine and Russia have boasted of staggering numbers of foreign volunteers and mercenaries willing to join the biggest conflict in Europe since the Second World War. On March 6th, Ukraine announced that some twenty thousand people from fifty-two countries had applied to fight in the newly formed International Legion of Territorial Defense of Ukraine. They reportedly include Americans, Canadians, and several European nationalities. “The whole world today is on Ukraine’s side, not only in words but in deeds,” the Foreign Minister, Dmytro Kuleba, told Ukrainian television.

Days later, the Russian Defense Minister, Sergei Shoigu, claimed that some sixteen thousand men from the Middle East had applied to fight for Russia. “As for the mercenaries from all over the world being sent to Ukraine, we see that they do not conceal it, the Western sponsors of Ukraine, the Ukrainian regime, do not hide it,” Putin said, in a meeting with his top security advisers. “That’s why if you see that there are people who are willing to come as volunteers, especially not for money, and help people residing in Donbas, well, we need to meet them halfway and assist them in moving to the combat zone.”

The infusion of outsiders and “irregular forces” could further complicate an already messy conflict, according to a report released on Monday by the Soufan Center, a nonprofit, global-security research group. “The battlefield in Ukraine is incredibly complex, with a range of violent non-state actors—private military contractors, foreign fighters, volunteers, mercenaries, extremists, and terrorist groups—all in the mix,” it concluded. In the lexicon of war, volunteers who join a rebel force or militia are typically called “foreign fighters,” while mercenaries are generally employed by a state and fight for profit or personal gain. The U.S. and the U.N. deemed the tens of thousands who joined ISIS in Syria and Iraq foreign terrorist fighters, not mercenaries. But such definitions are tricky—and easily contested. The Russian Defense Ministry has referred to any foreigners caught in Ukraine’s International Legion as mercenaries—who will not be eligible for protections as prisoners of war under the Geneva Conventions. “At best, they can expect to be prosecuted as criminals,” the Defense Ministry announced. To drive home the point, on March 13th, Russia launched missiles at a base near Ukraine’s border with Poland that it described as a “training facility for Western mercenaries.”

The looming question at this strategic juncture of the war is how—or whether—foreign fighters and mercenaries will alter the conflict’s course. Experts believe that the estimates by both Ukraine and Russia are high, more a wish list than reality. By mid-March, hundreds of foreigners showed up to fight for Ukraine, not thousands. Over time, foreign fighters have the potential to be “force multipliers,” Colin P. Clarke, a senior research fellow at the Soufan Center who co-wrote the report, told me. “But that’s in the rare case that you have somebody that’s highly trained and motivated,” such as former member of U.S. or British special forces. “These are people that actually know irregular warfare, that can really have an impact on strategy,” he said.

Others who come often serve as “cannon fodder,” and cause “more harm than they’re worth because of the lack of experience, because they’re essentially war tourists that are going there for a selfie and a story,” Clarke told me. Some have complained about weapons shortages, and the language gap has hindered integration with Ukrainian forces on the front lines. The Ukrainians, Clarke added, have tried to discourage volunteers without military experience, partly because they risk being captured and exploited by Russian propaganda. The State Department has warned Americans not to travel to Ukraine—for any reason—since they face “the very real risk” of capture, criminal prosecution, or death. (Some foreign fighters—“jarred by the horrors and brutalities of war”—have already opted out of Ukraine, the Soufan Center reported.)

Under the Russian constitution, the use of private military companies is technically illegal. The Kremlin denies that the Wagner Group even exists. Prigozhin has also denied ties to the organization, although in 2021 the European Union formally claimed that he financed it. Putin has reportedly made mercenaries part of Moscow’s military strategy since it first intervened in Ukraine, in 2014, to seize Crimea, and to support the pro-Russia separatists in Donbas. The Wagner Group was created to aid, stand in for, and provide plausible deniability to Russian forces. Moscow eventually recruited more than thirteen thousand fighters from several countries to fight in Donbas, according to the Soufan Center.

Putin’s reliance on Prigozhin, the Wagner Group, and other private military contractors has since “exploded,” with “suspected or proven” military operations in thirty countries on four continents, from Venezuela to Libya and Afghanistan, according to the Center for Strategic and International Studies. The Wagner Group has recruited, trained, and deployed operatives worldwide to project power, undermine the U.S., and increase Moscow’s influence using lower-profile contractors. In 2021, the Council of the European Union alleged that the Wagner Group has also been used “to fuel violence, loot natural resources and intimidate civilians in violation of international law.”

Within the first ten days of Russia’s invasion, it deployed an estimated thousand mercenaries from the Wagner Group, a U.S. official told me. But they quickly suffered losses, too. By early March, about two hundred mercenaries, some of whom belonged to the group, had already died on the battlefield, the official said. Russia is also recruiting in Syria, where its forces have propped up President Bashar al-Assad since 2015. Syria’s eleven-year civil war has produced informal local militias as well as battle-hardened soldiers who earn as little as fifteen to thirty-five dollars monthly; Russia is reportedly promising a thousand dollars or more a month to fight in Ukraine. The Syrians alone, however, may not make a strategic difference, experts say. They don’t speak the language or know the terrain in Ukraine. The Assad regime needed its own foreign fighters, from militias in Lebanon and Iraq, as well as strategists from Iran and Russia.

The Russian military seems to be gambling on outside help. As of mid-March, “nearly 90% of the Wagner Group’s manpower and resources have been moved from other theaters into Ukraine,” the Soufan Center reported. Yet Moscow’s recruitment of foreigners reflects desperation, Clarke told me. “They actually need those bodies to take the place of the conscripts that are dying in large numbers.” On Monday, the Pentagon said the Wagner Group’s contract soldiers were focussed on the Donbas as Russia shifts its attention from capturing Kyiv, the capital, to widening its hold in the resource-rich east and along the southern coastline. A different phase of the war has begun, with a growing array of players.