BUNNIK, Netherlands — Detailed analysis of video images has established that the Buk missile that brought down Malaysia Airlines Flight 17nearly four years ago came from a Russia-based military unit, according to an international team of investigators.

Wilbert Paulissen of the Dutch National Police said Thursday that the missile was from the Russian military's 53rd anti-aircraft missile brigade, which is based in the Russian city of Kursk.

"All the vehicles in a convoy carrying the missile were part of the Russian armed forces," he told a televised news conference.

Paulissen was speaking at a presentation of interim results of the long-running investigation into the downing of flight MH17.

The reconstructed wreckage of MH17 in the Netherlands in 2015. Michael Kooren

The passenger jet was headed from Amsterdam to Kuala Lumpur, Malaysia, when it was was blown out of the sky over eastern Ukraine on July 17, 2014. All 298 passengers and crew were killed.

Russia has always denied involvement in the downing of the jet.