Russian President Vladimir Putin pledged Friday to make public the findings of Moscow’s investigation into the crash of a transport plane that he alleged Kyiv’s forces shot down despite having been informed that Ukrainian prisoners of war were on board.

In his first public remarks on Wednesday’s crash, Putin repeated previous comments by Russian officials that “everything was planned” for a prisoner exchange that day when the IL-76 military transport went down in a rural area of Russia’s Belgorod region with 65 Ukrainian POWs on board.

“Knowing (the POWs were aboard), they attacked this plane. I don’t know whether they did it on purpose or by mistake, through thoughtlessness,” Putin said of Ukraine at a meeting with students.

Authorities in the Belgorod region, which borders Ukraine, said all 74 people on the plane, including six crew members and three Russian servicemen, were killed when the aircraft crashed in a huge ball of flames.

Putin offered no details to support the allegation that Ukraine was to blame, which other Russian officials have also made. Ukrainian officials have not said whether their military shot down the plane, but they called for an international investigation. Independent verification of Moscow’s claim was not possible.

Both sides in Russia’s 23-month-long war in Ukraine have often used accusations to sway opinion at home and abroad. Wednesday’s crash triggered a spate of claims and counterclaims, but neither of the warring countries offered evidence for its accusations.

Ukrainian officials confirmed that a prisoner exchange was due to happen Wednesday but said it was called off. They cast doubt on whether POWs were on the IL-76 and put forward their own theories about what happened.

They also implied that the plane may have posed a threat. They said Moscow did not ask for any specific airspace to be kept safe for a certain length of time, as it has for past prisoner exchanges.

Mykola Oleshchuk, Ukraine’s air force commander, described Moscow’s claims as “rampant Russian propaganda.”

Putin said the plane’s flight recorders had been found and Russian investigators’ findings will be published.

“There are black boxes, everything will now be collected and shown,” Putin said. “I will ask the investigative committee to make public, to the maximum extent possible, all the circumstances of this crime — so that people in Ukraine know what really happened.”

Ukrainian President Volodymyr Zelenskyy has requested an international investigation.