International investigators probing the downing of Malaysian Airlines flight MH17 made their interim findings public on Thursday in the Dutch town of Bunnik.

A surface-to-air missile shot down MH17 on July 17, 2014, over Ukrainian territory, killing all 298 passengers and crew on board. The majority of the passengers were Dutch nationals. The Boeing 777 was on a routine flight between Amsterdam and Kuala Lumpur.

The findings of the investigation:

• The Buk missile that brought down Malaysia Airlines Flight 17 was transported from a Russian military brigade.
• The missile was fired from the Russian military's 53rd anti-aircraft missile brigade based in the Russian city of Kursk.
• All the vehicles in a convoy carrying the missile were part of the Russian armed forces.

'Still work to be done'

Chief investigator Fred Westerbeke said the probe was now in its "last phase" but added there was "still work to be done." He did not say how long the probe would take.

The investigators have presented their findings to Moscow and are seeking answers, but have yet to receive a response.

The team called on the public, including friends and families of the members of Russia's 53rd brigade, to assist in their inquiries into the incident and come forward with details about the crew operating the missile system.

'Important piece of the puzzle'

Responding to the latest findings, the Russian defense ministry said not a single Russian missile system had ever crossed its border with Ukraine, state-owned TASS news agency reported.

"It is clear that these gratuitous accusations are an attempt to discredit our nation in the eyes of the international community," the Russian foreign ministry said in a statement.

Dutch Prime Minister Mark Rutte said he would shorten his visit to India by a day in order to join a cabinet meeting on Friday to discuss the new findings.

How countries who lost men and women in the MH17 tragedy reacted

• Dutch Foreign Minister Stef Blok called the latest findings "an important piece of the puzzle," adding that he is "very impressed by the evidence that has been collected."
• Belgian Foreign Minister Didier Reynders called on all countries to cooperate fully with the probe "so that those responsible can be brought to justice."
• Australian Foreign Minister Julie Bishop said the findings "should be of grave international concern. We are discussing these findings with our partners and considering our options."
• Ukranian President Petro Poroshenko said there is "every reason to expect that in the near future the Dutch prosecutor's office will be able to file a prosecution against the individuals involved in shooting down the plane."

Challenges galore: The latest findings take the investigation one crucial step further by identifying the exact Russian military unit allegedly involved. The next challenge would be to identify members of the crew who operated the missile and determine how high up the chain of command the order originated. But even if the investigators do manage to successfully identify the suspects, it would an onerous task to arrest and bring them to trial.

Online investigator Eliot Higgins, who founded Bellingcat, told DW on Thursday that investigators had to be very careful in building their case against Russia: "They needed to be 100 percent sure everything they presented was completely correct because just one error and the Russian government would go after them."

Higgins said there were multiple matches from the evidence: "We know this missile launched in a convoy going to the border with Ukraine. It is completely improbable there was another, identical missile launcher with the same markings that exists anywhere in the world, let alone in that location."

Who conducted the investigation? The Joint Investigation Team consists of investigators from Australia, Belgium, Malaysia, the Netherlands and Ukraine.

What did the 2015 investigation conclude? The latest findings follow a 2015 report by the Dutch Safety Board which found that the aircraft was hit by a Russian-made Buk missile. The Russian government has consistently denied involvement in the incident.

How have the investigators built on 2015 findings? The latest investigation recreated the route taken by the missile convoy from Kursk across the border into Ukraine using videos and photos. The prosecutors have now identified the exact unit allegedly involved. Dutch investigator Wilbert Paulissen said on Thursday the team "ascertained that the Buk missile has a number of unique characteristics. These characteristics as such served as a type of fingerprint for the missile."

How many suspects are there? Dutch prosecutors said in 2016 they had identified 100 people of interest but did not reveal their identities. Investigators on Thursday said that had narrowed the list down to several dozen.

Where will suspects be prosecuted? Under an agreement reached with the countries taking part in the joint probe, any suspects arrested in the case will be prosecuted in the Netherlands.

ap/aw (Reuters, AP)