The crash of a Russian military plane close to the border with Ukraine was caught on film and widely shared on social media, but who was on board and what caused the crash is the subject of a bitter dispute.
Analysts say there are more questions than answers.
The Ilyushin Il-76 military transport carrier crashed in the western Russian region of Belgorod on Wednesday, with videos showing the aircraft falling from the sky on its side before crashing in a fireball.
"We do not know much about the downed Il-76. Despite early allegations of its flight number being RA-78830, we do not know yet where this plane was heading and where it came from," said Ivan Klyszcz, a researcher at the Estonia-based International Centre for Defence and Security.
"It was shot down to the northeast of Belgorod, but that is all we know."
Moscow announced, with uncharacteristic speed, that one of its planes had been shot down by Ukraine ahead of a planned prisoner exchange.
The Russian defence ministry said the plane was carrying 65 Ukrainian soldiers captured during Russia's invasion, as well as six crew members and three Russian military personnel.
Russia's Investigative Committee said Thursday that it had opened a "terrorism" inquiry into the crash.
Military expert Michael Nacke, who runs a widely followed YouTube channel critical of Russia's invasion, said evidence so far suggested that the plane had been shot down by Ukraine.
"It can be stated with a high degree of certainty that the plane was shot down by Ukraine's armed forces," he said, pointing to the nature of Ukraine's reactions throughout the day.
A Moscow-based independent military analyst, who requested anonymity to speak freely, also said the plane was "probably" shot down by Ukraine but declined to comment further.
"This is strange business. We might never find out the whole truth," the analyst told AFP.
The Ukrainian authorities confirmed a prisoner swap was due to occur Wednesday. But they did not confirm the presence of any prisoners on board, nor claim responsibility for the aircraft's destruction. President Volodymyr Zelensky called for an international investigation, and Kyiv opened a criminal inquiry.
Ukrainian media initially cited defence sources saying that the Ukrainian army had downed the plane, and that it was carrying ammunition for S-300 missile systems. The claim was later retracted.
In a statement published hours after the crash, the Ukrainian army said it would continue to target Russian aircraft in the region of Belgorod.
Nacke said that for him, the absence of an official declaration of Ukraine's non-involvement in the plane's demise was a "clear sign that the Ukrainian armed forces had hit the plane", using either an S-300 or Patriot PAC2 missile system.
The Institute for the Study of War (ISW) said Wednesday that Russia was already "seizing on the Il-76 crash to sow domestic discontent in Ukraine and undermine Western will to continue giving military support to Ukraine".
Analysts say it remains unclear if Ukrainian POWs were on board.
Nacke said he had seen pictures from the site crash showing two bodies, which "of course does not match the reported death toll from the crash".
Ukraine says Moscow did not inform Kyiv that any POWs would be transported by plane, which would be a requirement in accordance with the Geneva Conventions. Moscow insists Kyiv had been warned.
Margarita Simonyan, editor in chief of Russia's state-backed RT channel, published a list of Ukrainian POWs allegedly on board the plane -- But several Russian and Ukrainian sources said at least one of them had already been exchanged in an earlier swap.
"The 'evidence' presented so far by Russia is unpersuasive," Klyszcz said.
Ukraine's military intelligence spokesman Andriy Yusov said the plane might have carried both missiles and Ukrainian prisoners of war, who might have been used as "human shields for the transportation of ammunition".
Speaking to Radio Svoboda, part of the US-funded Radio Free Europe/Radio Liberty, Yusov also did not rule out a "deliberate provocation", claiming that several high-ranking Russian officials were warned not to board the aircraft at the last minute.
But the Moscow-based analyst said he was sceptical about a possible Russian trap.
"Not that it's impossible," he said. "But I doubt this is what has been planned," since an Il-76 and its crew were "too valuable a resource" for Moscow in wartime.
"And prisoners suitable for an exchange are not such a disposable resource."
