MOSCOW >> Russia’s military said today that it was looking into whether one of its airstrikes in the Syrian desert had killed Abu Bakr al-Baghdadi, the self-declared caliph of the Islamic State.

In a statement, the Defense Ministry said that the Russian air force struck a meeting of Islamic State leaders May 28 outside Raqqa, Syria, the group’s de facto capital, possibly killing al-Baghdadi.

The statement offered no explanation for the two-week delay in publicizing the airstrike. And it was also not clear whether the Russian military had known in advance that al-Baghdadi was at the gathering, or had learned of this possibility only after the strike was carried out.

Rumors of al-Baghdadi’s death had circulated for months before the Russian announcement. But a Pentagon spokesman, Capt. Jeff Davis of the Navy, said today: “We have no information to corroborate those reports.”

A senior Defense Department official confirmed today that Russian warplanes were “very active” carrying out airstrikes in the area south of Raqqa where Russian officials say al-Baghdadi may have been killed.

But the official, echoing public statements from the Pentagon, said he could not corroborate Russian reports of Baghdadi’s death.

Col. Ryan S. Dillon, a spokesman for the U.S.-led coalition fighting the Islamic State in Syria and Iraq, said that U.S. air commanders in Qatar speak almost daily on a special hotline with their Russian counterparts, primarily to avoid any midair accidents by warplanes flying missions in Syria. He said in an interview that analysts were now going back over the reports from May 28 and the subsequent days to see what the Russians had said about flight operations.

Nothing has been heard from al-Baghdadi publicly since November, when the Islamic State released a blistering audio recording in which he urged forces to remain firm in the face of the U.S.-backed Iraqi offensive in Mosul.

Rami Abdul Rahman, founder of the Syrian Observatory for Human Rights, which closely monitors military operations in Syria, said it had no record of senior Islamic State leaders being in the area around Raqqa at the time of the strike. “It’s illogical for ISIS senior leaders to stay in Raqqa amid this military operation,” he said, adding that senior leaders had already decamped southeast, to the area around the city of Deir el-Zour, closer to the border with Iraq.

Laith Alkhouri, a director at Flashpoint, a business risk intelligence company in New York that tracks militant threats and cyberthreats, also expressed skepticism.

“At this time, I’m not seeing credible chatter to verify the claim by Russia,” he said. “Al-Baghdadi has been claimed killed multiple times before, and none of the previous claims proved legitimate.”

Russia’s foreign minister, Sergey Lavrov, himself introduced a note of caution when asked about the Russian military’s reports. “So far, I do not have 100 percent confirmation of this information,” he said at a news conference.

Lavrov also cautioned that the Islamic State was likely to survive the possible 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 said at 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 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.