An explosion on a plane believed to be carrying the Russian mercenary leader Yevgeny V. Prigozhin likely brought down the aircraft on Wednesday, killing all the passengers aboard, according to U.S. and other Western officials citing preliminary intelligence.
A definitive conclusion has not yet been reached, but a blast is the leading theory of what caused a private plane to crash in a field between Moscow and St. Petersburg. The explosion could have been caused by a bomb or other device planted on the aircraft, though other theories, like adulterated fuel, were also being explored, the officials, who spoke on the condition of anonymity to discuss the matter, said.
U.S. officials sounded increasingly certain, both publicly and privately, that Mr. Prigozhin was dead, and that President Vladimir V. Putin of Russia had ordered the killing, intent on removing a figure who had led a short-lived mutiny in June that was seen as the gravest challenge to Mr. Putin’s rule in decades.
Brig. Gen. Patrick Ryder, the Pentagon press secretary, said the initial U.S. assessment, based on a “variety of factors,” was that Mr. Prigozhin had likely been killed in the crash.
General Ryder did not state a theory for the crash, but said the United States had no information to indicate that a surface-to-air missile brought down the plane. Other officials said American satellite intelligence did not detect a missile launch, and there was no other evidence to suggest a surface-to-air weapon took out the plane. Western governments continue to explore the possibility that an air-to-air missile could have been used, even if an explosion on board remained the more likely scenario.
Analysis by The New York Times of flight data and video from the crash indicates there was most likely at least one catastrophic midair event that occurred several minutes before the private jet crashed. The precipitous drop and widespread debris, experts say, point to an explosion or sudden breaking apart of the aircraft rather than a mechanical failure.
Officials said it appeared probable that Mr. Putin ordered the assassination of Mr. Prigozhin at the same time or shortly after the Russian president removed Gen. Sergei Surovikin from his military command.
The plane crash came only hours after Russian authorities said that General Surovikin had been relieved of his post. General Surovikin, like Mr. Prigozhin, was seen as ruthlessly effective in the Ukraine war. As an ally of Mr. Prigozhin, General Surovikin at least knew about the mercenary leader’s plans and may have even assisted in the rebellion, according to U.S. officials.
During the mutiny, forces from the Wagner paramilitary group, which Mr. Prigozhin founded, took over a key southern city and an armed convoy of mercenaries marched toward Moscow. While Mr. Putin denounced Mr. Prigozhin and the organizers of the rebellion for “betraying their country,” some analysts said the episode made Mr. Putin look weak.
In public comments on Thursday, Mr. Putin did not explicitly confirm the Wagner leader’s death, but he offered his condolences to the families of those who had perished in the crash and said that Russian investigators would pursue the investigation into it “to the end.”
Mr. Putin referred to Mr. Prigozhin in the past tense: “This was a person with a complicated fate. He made some serious mistakes in life, but he also achieved necessary results.”
Rather than focusing on Mr. Prigozhin’s aborted mutiny, Mr. Putin spoke of Wagner’s effort in Ukraine. Under Mr. Prigozhin’s direction, the paramilitary group played a vital role in taking Bakhmut, the most significant Russian advance in Ukraine since last summer.
On Thursday, Russian news outlets and propaganda efforts focused on the idea that the crashed plane had been brought down by an accident. The information campaign gradually took hold on Russian social media, overwhelming posts speculating that Mr. Prigozhin had been killed on orders of Mr. Putin or by a bomb on the plane, according to Jonathan Teubner, the chief executive of FilterLabs AI, which tracks public sentiment in Russia.
Russian internet posts also contained clues about what might have brought down the plane.
Videos posted on the messaging app Telegram show debris from the aircraft in three locations that span across two miles. One site contains the main fuselage of the aircraft, an Embraer Legacy 600, one contains the tail section, and a third contains a piece of smaller debris. The locations of the debris roughly align with the aircraft’s direction of travel.
Raw flight tracking data from FlightRadar24 shows the plane experienced a sudden drop in altitude around 6:19 p.m. local time. The aircraft remained in the air for some time before free falling from the sky approximately 30 miles (48 kilometers) away, according to an analysis of video capturing the crash and debris fields.
“Having a debris field that large is unusual if the plane hadn’t taken any structural damage while airborne,” said Ian Williams, the deputy director of the Missile Defense Project at the Center for Strategic and International Studies.
The Times analysis did not confirm exactly what brought the aircraft down, but did not find evidence of a routine mechanical malfunction.
“Planes don’t often fall straight out of the sky, like straight down like that, unless there’s been something to stop its forward momentum,” Mr. Williams said.
U.S. officials are tracking closely what might become of the Wagner group without Mr. Prigozhin and other key leaders. In addition to Mr. Prigozhin, Dmitry Utkin, a former special forces and intelligence officer who was Wagner’s second in command, is believed to have died in the plane crash, along with other top officials of the mercenary group.
Speaking to reporters on Thursday. Gen. Mark A. Milley, the chairman of the Joint Chiefs of Staff, said there would most likely be repercussions in countries where Wagner has put troops.
“If the leadership of Wagner is suddenly killed, there is going to be an effect,” General Milley said. “What that impact is, I don’t know yet.”
While Mr. Prigozhin had pulled his forces out of the fight in Ukraine, Wagner remains active in Africa, one of the primary ways Russia has expanded its influence on the continent.
Though Mr. Prigozhin was seen as an enemy of the United States, American officials had watched with interest how Mr. Prigozhin had become a thorn in Mr. Putin’s side. As a result, American officials said, Mr. Putin clearly thought he had no choice but to take action.
But officials were divided on Thursday over whether Mr. Putin would emerge stronger or weaker inside Russia, and some simply did not want to entertain the question.
Officials were looking closely at how much of the Wagner group Mr. Putin would be able to bring under his command. One of the causes of the mutiny was an effort by the Russian defense ministry to demand that any Russians fighting in Ukraine work for the government. Since the rebellion, the Kremlin has worked to bring Wagner forces under its control.
One U.S. official said that in the aftermath of Mr. Prigozhin’s presumed death, Mr. Putin could struggle to put an ally in charge. Wagner, the official said, was likely to choose its new leader — most likely one loyal to Mr. Prigozhin.
Anton Troianovski contributed reporting from London, and John Ismay from Washington.