Updated

The Russian military said on Monday that the missile that shot down Malaysia Airlines Flight 17, killing all 298 people on board, came from the arsenals of the Ukrainian army, not from Russia.

The jet was shot down by a Soviet-made missile over rebel-held eastern Ukraine in July 2014, about 40 kilometers (25 miles) from the Russian border, where fighting had been raging for months between Ukrainian forces and Russian-backed separatists.

The Netherlands and Australia announced in May that they believe the missile was transported to Ukraine from a military unit in the Russian city of Kursk.

Russia has vehemently denied involvement and has over the years come up with various theories as to the cause of the crash, generally laying the blame on the Ukrainian side.

Lt. Gen. Nikolai Parshin, chief of the Missile and Artillery Directorate at the Russian Defense Ministry, told reporters on Monday that the military had studied and declassified archives at the research center outside Moscow that produced the Buk missiles after the Dutch investigators displayed parts of the missile and their serial numbers. Parshin said the Russian archives show that the missile that was made of these parts was transported to a military unit in western Ukraine in 1986, and to Russia's knowledge never left Ukraine.

Asked about the possibility that the separatists may have seized the missile system during fighting in 2014, Defense Ministry spokesman Maj. Gen. Igor Konashenkov conceded that Russia does not have any documents proving otherwise but pointed to the statements of Ukrainian officials who have denied that separatists seized any of their Buks.

The separatists in the weeks prior to the plane crash bragged on social media about shooting down Ukrainian military aircraft. On the day that MH17 crashed, a rebel commander posted that his troops had shot down a Ukrainian military plane. He later said his account has been hacked and that the rebels did not shoot down any aircraft that day.

A highly placed rebel, speaking to the AP shortly after the crash, admitted that rebels were responsible. The rebels believed they were targeting a Ukrainian military plane, the person said. He did not speculate, however, on a possible role of the Russian military in the attack.

The Russian military did provide material assistance to the rebels, and journalists sighted sophisticated weapons in the separatist-controlled areas that were never in Ukraine's arsenals.

Oleksandr Turchynov, secretary of Ukraine's Security and Defense Council, said on Monday that Russia's claim is "yet another failed fake report that the Kremlin made up in order to cover up their crime that has been proven by the official investigation as well as independent experts."

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Yuras Karmanau contributed to this report from Kiev, Ukraine.