The missile that downed a Malaysia Airlines flight over eastern Ukraine in 2014 belonged to a Russian brigade, international investigators say.
For the first time, the Dutch-led team said the missile had come from a unit based in western Russia.
All 298 people on board the Boeing 777 died when it broke apart in mid-air flying from Amsterdam to Kuala Lumpur.
It was hit by a missile fired from rebel-held territory in Ukraine. Russia says none of its weapons was used.
But on Thursday Wilbert Paulissen, a Dutch official from the Joint Investigation Team (JIT), told reporters: "All the vehicles in a convoy carrying the missile were part of the Russian armed forces."
He said that after studying all available photos and footage, investigators had been able to trace the convoy to Russia's 53rd brigade, which consists of 300 people based in the city of Kursk.
