Russia’s military said on Friday that it was looking into whether a Russian airstrike in the Syrian desert killed Abu Bakr al-Baghdadi, the self-declared caliph of the Islamic State, in what would be a major military achievement.
In a statement, the Defense Ministry said that the Russian Air Force struck a meeting of Islamic State leaders on May 28 outside Raqqa, Syria, the group’s de facto capital, possibly killing Mr. Baghdadi, one of the world’s most wanted terrorists.
Mr. Baghdadi’s death has been the subject of many past rumors, and the United States-led coalition fighting the Islamic State in Syria and Iraq, said it could not back up the Russian account.
“We cannot confirm these reports at this time,” said Col. Ryan S. Dillon, a spokesman for the coalition.
In Washington, Pentagon officials also reacted with cautious skepticism, saying that they had seen nothing in their classified reporting channels over the past two weeks that would support Moscow’s contentions. But the officials said that intelligence and military analysts were now going back over the reports, including any on flights by Russian aircraft near Raqqa on May 28.
The Russian statement was itself written cautiously, suggesting that the military remained uncertain about whether its strike had killed Mr. Baghdadi, a prize sought by several countries in the long struggle against the Islamic State.
“According to information which we are checking through various channels, the leader of the Islamic State, Abu Bakr al-Baghdadi, was at the meeting and the strike destroyed him,” the statement said.
Russia’s foreign minister, Sergey V. Lavrov, introduced a note of caution while speaking at a news conference in Moscow. “Of course, I have heard these reports,” Mr. Lavrov said. “So far, I do not have 100 percent confirmation of this information.”
Mr. Lavrov also cautioned that the Islamic State was likely to survive the death of its leader. “Examples of such actions to destroy or ‘behead’ a terrorist group have always been presented with great enthusiasm,” he said. “However, history shows that the fighting capacity of these structures was restored.”
Russia intervened in the Syrian civil war in 2015; it saidat first that cargo planes flying to a Syrian air base carried only humanitarian aid, but later openly announced a military operation. The Kremlin’s stated goal was fighting the Islamic State, lest it gain a stronghold in Syria not far from restive, predominantly Muslim regions in southern Russia.
But the Obama administration said that the pattern of airstrikes showed that Russia’s real intention was to prop up the government of President Bashar al-Assad, a Russian ally battling a range of opposition groups, including moderate rebels. The killing of the Islamic State’s leader, if confirmed, would help bolster Russia’s initial justification for its intervention — that its goal all along was to fight terrorism.
It was not clear whether the Russian military knew in advance that Mr. Baghdadi was at the gathering, or learned of this possibility only after the strike. The Russian Defense Ministry said that it had “warned the American side about the strike in advance,” but it was unclear whether Russia had shared intelligence on the meeting or cooperated in any other way with the Western-led coalition fighting in Syria.
Russia is believed to have an extensive intelligence operation targeting the Islamic State that makes use of the large numbers of Muslims from former Soviet states who have joined the group. A former Islamic State military commander, for example, was an ethnic Chechen from Georgia.
Whether this window into the Islamic State’s activities helped the Russian military to target the airstrike was not clear.
The Russian military said two models of Sukhoi fighter jets, Su-34s and Su-35s, had carried out the strike, on what it described as “high level commanders of the terrorist group within the so-called military council of the Islamic State,” Interfax reported.
The strike also killed 30 field commanders and as many as 300 fighters, the military said. The strike lasted from 12:35 a.m. until 12:45 a.m., according to Interfax.
Russia learned of the meeting late in May, and while verifying the information ascertained that the commanders intended to discuss the retreat of their fighters from Raqqa, the Defense Ministry said.
The extent to which Mr. Baghdadi exerted day-to-day control over the Islamic State’s activities is not fully clear, but his death would be a major blow, easily the most prominent since Osama bin Laden, the leader of Al Qaeda, was killed in an American operation in Pakistan in 2011.
Mr. Baghdadi, who is believed to have been born in Iraq in 1971, grew up under Saddam Hussein’s regime. After the United States invaded the country and toppled Mr. Hussein in 2003, Mr. Baghdadi spent years imprisoned at Camp Bucca in southern Iraq.
He emerged from the jumble of Sunni extremist elements that battled the American forces and Iraq’s new Shiite-led government in the decade after the invasion. He was a follower of the Jordanian militant Abu Musab al-Zarqawi, who formed a branch of Al Qaeda in Iraq, but eventually fell out with Al Qaeda because his wanton killings of Shiites were too brutal even by Qaeda standards.
The American military and Sunni tribesmen, banded together in what became known as the Awakening, left Al Qaeda, the Islamic State and other Sunni jihadists in disarray by 2010, but with an American troop withdrawal looming in 2011, tensions between Sunnis and the Shiite-dominated government of Prime Minister Nuri al-Maliki soared.
Mr. Baghdadi was named the head of the Islamic State in 2010, and his group seemed particularly adroit at turning these tensions to its advantage. After the Arab Spring uprisings of 2011, Syria became a fertile ground for jihadists like Mr. Baghdadi, who exploited the power vacuum left by the violent challenge to President Bashar al-Assad’s rule. The group also displayed a sophisticated command of social media to recruit potential jihadists from around the world, and to sow terror in the West.
Using porous borders between Syria and Iraq, the new jihadists overpowered Shiite-led authorities and rival Sunni factions in both countries, and established a stronghold in an overwhelmingly Sunni area. In the summer of 2014, the group declared itself a caliphate, a successor to early leaders of Islam.
Mr. Baghdadi has not been seen publicly in quite some time, even as the governments of Iran, Iraq, Russia and the United States have pounded Islamic State strongholds in major cities and recaptured stretches of territory from the group.
One of Mr. Baghdadi’s closest associates — Abu Muhammad al-Adnani, who headed the group’s efforts to build a global terrorism network, including overseeing attacks in Paris and Brussels — was killed in an airstrike in August.
Raqqa has been under attack in recent weeks: American-backed Kurdish and Arab forces, have been closing in on the ground, and an American-led coalition of Western and Arab air forces has attacked the city from above.
In the past, Russian state news agencies have reported inaccurately on the deaths of Islamic separatists in the Chechen conflict.
In 2011, for example, several Russian wire agencies citing anonymous sources reported that Doku Umarov, a leader of the Chechen insurgency, had been killed in an airstrike in the North Caucasus region, but there was never official confirmation. When Mr. Umarov died years later — in murky circumstances, months before the 2014 Winter Olympics in Sochi, Russia — the Russian authorities made no official announcement, perhaps to avoid reminding visitors about the threat. Instead, Islamist group he had led, the Emirate of the Caucasus, eventually reported his death on a website.