The Russians seem to be “trying to change the narrative of their intervention in Syria to actually doing what they’ve been saying they’ve been doing, but not, for two years”: fighting terrorists, said the Atlantic Council’s John Herbst, who co-authored a report last year on how Vladimir Putin’s war has primarily involved defending Syrian President Bashar al-Assad. (The Russian government argues that all forces opposed to Assad are “terrorists,” but it’s been focusing on anti-government rebels—including factions supported by the United States—rather than ISIS.)

So what explains Russia’s sudden attention to ISIS—and why hasn’t it translated into better relations with the United States?

Genevieve Casagrande, a Syria analyst at the Institute for the Study of War (ISW), has one deeply skeptical theory. She’s not entirely convinced that the Russian airstrikes occurred, let alone that they took out Baghdadi and could signal a shift in Russia’s involvement in the civil war. “The vast majority of Russian airstrikes inside Syria have targeted the Syrian opposition” to Assad, Casagrande told me, and the Kremlin has repeatedly released disinformation about who they’re targeting—be it civilians or moderate rebel forces.

Casagrande’s organization maps Russian strikes in Syria by gathering official statements, on-the-ground accounts, and open-source intelligence. “We will collect airstrikes that have 20 to 30 different reports of what the airstrike was, what it hit, photos of the plane, accounts about the high-pitched sound of the plane or how many [planes] were flying in the group, etc.,” she said. And ISW researchers have seen only “fairly minimal” evidence so far of a Russian strike near Raqqa on May 28, the day when the Russian military claims to have maybe killed Baghdadi. “It doesn’t mean it didn’t happen,” she acknowledged, particularly since ISW’s network of activists is thin in that region of Syria. But at this point, “it’s a rumored strike for us at best.” (U.S. officials have similarly been unable to confirm the reports, and some activist groups have described a strike in the area in ways that differ substantially from the Russian account.)

“Russia is not in Syria to defeat ISIS,” Casagrande said, even though ISIS has attacked Russians and poses a serious threat to the country. Russia is in Syria to prop up its ally, the Assad government, and by extension to maintain its geopolitical influence in the Middle East and military presence on the Mediterranean Sea. Despite losing their stronghold of Aleppo in December, opposition fighters—not ISIS—are still the greatest threat to the Assad government and thus to the Russians, she argued.

“Russia likes to portray itself as this marvelous counterterrorism actor that is in parallel and in lockstep with the U.S. against ISIS,” Casagrande said, in part because doing so positions Russia as a critical player in providing security in the Middle East. As my colleague Julia Ioffe has noted, Russia has cultivated an image as the West’s indispensable ally on counterterrorism at least since September 11, 2001. But “Russia typically only goes after ISIS when it is convenient for Russia,” according to Casagrande.