After an exhaustive, 15-month investigation, the Dutch Safety Board affirmed on Tuesday what has long been generally known or suspected — that Malaysia Airlines Flight 17 was shot down over eastern Ukraine on July 17, 2014, by a Russian-made Buk surface-to-air missile.

Even Russia, which has spent much of those 15 months generating all kinds of implausible theories that put the blame for the crash and its 298 victims on Ukraine, and doing its best to thwart investigations, has had to acknowledge that this is what happened. But it now argues that the fatal missile was an older model that the Russian armed forces no longer use, and that it was fired from territory controlled by the Ukrainian government.

The five-nation team led by the Dutch Safety Board did not assign responsibility. That will be the job of Dutch prosecutors. But the board’s minutely detailed report is consistent with theories advanced by the United States and Ukraine as well as evidence collected by the independent investigative website Bellingcat.com, which hold that the fatal missile was fired from territory controlled by Russian-backed rebels in eastern Ukraine.

In one key detail, the Dutch report undermined Russia’s competing claim. The Russian corporation that manufactures Buk missiles, Almaz-Antey, held its own news conference on Tuesday at which it said it had detonated a warhead of the sort used to arm the Buk missile identified by the Dutch alongside a decommissioned Russian jetliner to demonstrate that this explosion would pepper the plane with bowtie-shape shrapnel, which it said was not found at the crash site. But in fact, the Dutch board said it had discovered fragments of that exact shape, including some in the bodies of the cockpit crew.