Malaysia Airlines Flight MH17 was hit by a Russian-made Buk missile, causing the crash that killed all 298 people aboard the plane, the Dutch Safety Board (DSB) said in a report released Tuesday.
"Flight MH17 crashed as a result of the detonation of a warhead outside the airplane," DSB Chairman Tjibbe Joustra said at a press conference at the Gilze Rijen airbase in the Netherlands.
The long-anticipated report on the July 17, 2014, crash, found that those on board — 80 of whom were children — most likely lost consciousness immediately after a 9N314M-model warhead carried on a 9M38-series missile detonated outside the left side of the plane's cockpit, which then broke off from the rest of the aircraft.
The wreckage of Flight MH17 then landed in eastern Ukraine, in territory held by pro-Russian rebels fighting against the Western-backed government in Kiev. Each side has since blamed the other for downing the aircraft.
The missile was fired from a 320 square kilometer (123.5 square mile) area in the eastern part of Ukraine, said Joustra as he stood before a reconstruction of the plane built from debris collected from the crash zone.
However, he said additional investigations were needed to determine the exact location from which the missile was fired.
"The Board is aware that this [report] does not answer one important question -- the question of who is to blame for the crash," the report reads. "It is the task of the criminal investigation to provide that answer."
The Dutch prosecutor's office is expected to release a report in 2016 exploring who shot down the plane.
Of those killed on the Amsterdam to Kuala Lumpur flight, 193 were Dutch citizens. Additionally, 43 Malaysians, 27 Australians, 12 Indonesians, and 12 U.K. citizens were killed.
Prior to the release of the report, Dutch officials met privately with the families of the victims to share the findings of their 15-month investigation.
Barry Sweeney, whose son Liam died in the crash, told the BBC that officials told the families that it was unlikely their loved ones were conscious for long.
"We can't be 100% certain but we think that was the case," Sweeney said. "We have to think they didn't suffer."
The safety board chairman was highly critical of the decision to allow the plane to fly through the airspace in eastern Ukraine while an armed conflict was occurring.
"Why was Malaysia Airlines flight MH17 flying over an area where an armed conflict was taking place?" he asked. "Because no one thought civil aviation was at risk."
"In the opinion of the Dutch Safety Board, there was sufficient reason to close the airspace as a precaution," he said. "The Ukrainian authorities failed to do so."
The report concludes that the aviation industry "should take urgent measures to identify, assess, and manage the risks associated with flying over conflict zones immediately."
The safety board report also investigated the possibility the flight was downed by a bomb onboard the plane or due to an attack by another aircraft, as some rebels have claimed, but ultimately rejected these suggestions.
It instead found that a surface-to-air Buk missile detonated less than a yard from the left hand side of the cockpit.
The final milliseconds of the cockpit voice recorder captured "sound peaks" from the blast that investigators were able to use to triangulate the position of the explosion, Joustra said.
The three members of the crew inside the cockpit at the time of the explosion were killed immediately. Metallic objects from the warhead were found in the wreckage, as well as the bodies of the three people in the cockpit, Joustra said.
The safety board chairman said after the cockpit tore off, the tail section of the plane most likely crashed into the ground before the center section hit, landing upside down and catching fire.
Wreckage was scattered over an area of 50 square kilometers (19.3 square miles), with debris recovered as recently as two weeks ago, he said.
Joustra said it was likely that more pieces from the plane would continue to be found in the future.
The report found that after the plane's cockpit tore off, the passengers and crew on board were immediately exposed to "extreme factors" that most likely resulted in an immediate loss of consciousness or death.
"There was the deafening noise of the impact, abrupt deceleration and acceleration, decompression and the corresponding mist formation, reduced oxygen level, extreme cold, powerful airflow, the airplane's rapid descent and objects flying around," the report stated.
However, the report noted "it cannot be ruled out that some occupants remained conscious for some time during the one to one and a half minutes for which the crash lasted."
The DSB found no evidence, however, of conscious actions performed by those on board after the missile detonated. "It is likely that the occupants were barely able to comprehend the situation in which they found themselves," the report stated.
One passenger was found with an oxygen mask around the neck, but investigators could not determine if the passenger placed the mask there or it was done by someone on the ground after the passenger's death.
Meanwhile in Moscow, the Russian Buk missile manufacturer Almaz-Antey on Tuesday held a press conference to detail findings of its own investigation into the downing of MH17.
Rejecting the Dutch report before it was even released, the company said it had conducted an experiment on Oct. 7 that determined the Buk missile was an older model that belonged to the Ukrainian government and was fired from Ukrainian government-held territory, according to the Russian state-sponsored network RTV.
The release of the Russian findings was mocked by Joustra, according to a Guardian journalist. "It's always special when people already know that they don't agree with a report that's not even published yet," Joustra told reporters.
The Dutch investigators noted that they took into account Russia's objections to their findings as to what type of missile was used.
Russia's Foreign Ministry, however, called the Dutch report biased. "Russia regrets that despite its efforts to organize an MH17 probe, there are obvious attempts to carry out a political order," Deputy Foreign Minister Sergei Ryabkov said, according to the BBC. "The investigation was biased." Moscow vehemently opposes efforts to hold an international criminal tribunal into the crash, which it says would be prejudiced against Russia.
Ukraine's president, Petro Poroshenko, said the plane was "shot down from Russian-controlled territory from Russian weaponry," his press secretary tweeted.
A Ukrainian governmental commission released its own report Tuesday that said the missile was fired from Snizhne, a rebel-held where Associated Press reporters saw a Buk on the day of the crash a few hours before the plane was shot down. Gennady Zubko, the deputy prime minister in charge of the commission, said that the crash was a "planned terrorist attack."
Refuting the Dutch report, the Ukrainian commission claimed that there were no grounds to divert civilian aircraft away from the conflict zone, which 160 planes crossed on the day of the crash alone.
Arseny Yatsenyuk, Ukraine's prime minister, told a cabinet meeting that the crash was "an operation planned by Russian secret services," according to the government website. "We are convinced that this was carried out exclusively from the territories controlled by the Russian fighters, and there is no doubt that the drunk separatists can't operate Buk systems. That means these systems were operated exclusively by professional Russian troops," he said.
Ukraine and its Western backers are working out legal mechanisms to prosecute those it believes responsible, Yatsenyuk added. "The international investigative groups will do their work, and the people who got instructions from the Kremlin will be brought to justice," he said.
Writing on Twitter, British Foreign Secretary Philip Hammond commended the investigators on their report:
Prime Minister David Cameron also welcomed the report. "We have always been clear that justice must be done for all of the victims of MH17 and today's report brings us one step closer to establishing the truth," he said. "We, alongside our partners, will continue to send a clear message; those responsible for downing this plane will be held to account."
The White House also released a statement from National Security Council spokesman Ned Price praising the report.
Price called the DSB report "an important milestone in the effort to hold accountable those responsible for the shoot-down of the aircraft and the killing of those aboard."
"Our assessment is unchanged — MH17 was shot down by a surface-to-air missile fired from separatist-controlled territory in eastern Ukraine," he said. "The victims and their loved ones remain in our thoughts and prayers."
Max Seddon contributed to this report.