Putin also said that Russia, like Ukraine, wanted an international investigation into the incident.
Moscow accuses Kyiv of downing the Ilyushin Il-76 plane and of killing 74 people on board, including 65 captured Ukrainian soldiers it said were en route to be swapped for Russian prisoners of war.
Ukraine has neither confirmed nor denied that it downed the plane, and has demanded proof of who was on board.
"The plane was downed, and it's been definitively established by an American Patriot system - the expert analysis has already established that," said Putin.
"We insist that an international investigation be carried out. No international organisations are willing to do this," he added, saying Russia was officially asking for such an investigation.
He said that Ukraine had fired two missiles at the plane.
(Writing by Maxim Rodionov; Editing by Andrew Osborn)
