(CNN) Ukrainian authorities had "sufficient reason" to close the airspace over conflict-stricken eastern Ukraine before the downing of Malaysia Airlines Flight 17, according to the findings of a Dutch investigation into the crash.

The Boeing 777 was heading from Amsterdam to Malaysia when it was shot down on July 17, 2014, over Ukrainian territory controlled by pro-Russian separatists. All 298 people aboard the aircraft died in the crash.

The Dutch Safety Board (DSB) said whatever happened to the plane happened quickly, leaving the passengers dazed or unconscious. And while it's not clear if anyone died in midair, no one could have survived the plane's impact with the ground, the DSB said.

The DSB took the lead in the crash investigation at the request of Ukraine, which remains locked in conflict with pro-Russian separatists in its eastern Donetsk and Luhansk regions.

Previous incidents

The report said that between the end of April and July 17, 2014, Ukraine had reported that at least 16 of its forces' helicopters and planes had been shot down.

"During the period in which the conflict in the eastern part of Ukraine expanded into the airspace, neither Ukraine nor other states or international organizations issued any specific security warnings to civil aviation about the airspace above the eastern part of Ukraine," the DSB said.

"The weapon systems mentioned by the Ukrainian authorities in relation to the shooting down of these aircraft can pose a risk to civil aeroplanes, because they are capable of reaching their cruising altitude. However, no measures were taken to protect civil aeroplanes against these weapon systems," it said.

The decision-making process over Ukraine's airspace "was dominated by the interests of military aviation," it said.

The Prime Minister of Malaysia -- which lost 43 citizens in the crash -- issued a statement after the report's release. "Of the 160 flights that were on MH17's general route that day, not one was advised by the relevant authorities against any specific threat," Prime Minister Najib Razak said.

Buk rocket system

Announcing the board's findings at Gilze-Rijen airbase in the Netherlands, its chairman Tjibbe Joustra said: "As a precaution, there was sufficient reason for Ukraine authorities to close the airspace above the eastern part of the country where armed conflict was taking place."

Joustra said the warhead that downed the plane fit a Buk rocket system, referring to Russian military technology. But Russian officials who participated in the investigation said it was not possible to confirm the warhead or type of system, according to Joustra.

Photos: Malaysia Airlines Flight 17 crashes in Ukraine Photos: Malaysia Airlines Flight 17 crashes in Ukraine Debris from Malaysia Airlines Flight 17 sits in a field at the crash site in Hrabove, Ukraine, on September 9, 2014. The Boeing 777 was shot down July 17, 2014, over Ukrainian territory controlled by pro-Russian separatists. All 298 people on board were killed. In an October 2015 report, Dutch investigators found the flight was shot down by a warhead that fit a Buk rocket, referring to Russian technology, Dutch Safety Board Chairman Tjibbe Joustra said. Hide Caption 1 of 58 Photos: Malaysia Airlines Flight 17 crashes in Ukraine Australian and Dutch experts examine the area of the crash on August 3, 2014. Hide Caption 2 of 58 Photos: Malaysia Airlines Flight 17 crashes in Ukraine A woman walks with her bicycle near the crash site on August 2, 2014. Hide Caption 3 of 58 Photos: Malaysia Airlines Flight 17 crashes in Ukraine Police secure a refrigerated train loaded with bodies of passengers from Malaysia Airlines Flight 17 as it arrives in a Kharkiv, Ukraine, factory on July 22, 2014. Hide Caption 4 of 58 Photos: Malaysia Airlines Flight 17 crashes in Ukraine A pro-Russian rebel passes wreckage from the crashed jet near Hrabove on Monday, July 21, 2014. Hide Caption 5 of 58 Photos: Malaysia Airlines Flight 17 crashes in Ukraine – Wreckage from the jet lies in grass near Hrabove on July 21, 2014. Hide Caption 6 of 58 Photos: Malaysia Airlines Flight 17 crashes in Ukraine A man covers his face with a rag as members of the Organization for Security and Co-operation in Europe and the Dutch National Forensic Investigations Team inspect bodies in a refrigerated train near the crash site in eastern Ukraine on July 21, 2014. Hide Caption 7 of 58 Photos: Malaysia Airlines Flight 17 crashes in Ukraine Emergency workers carry a victim's body in a bag at the crash site on July 21, 2014. Hide Caption 8 of 58 Photos: Malaysia Airlines Flight 17 crashes in Ukraine A piece of the plane lies in the grass in eastern Ukraine's Donetsk region on July 21, 2014. Hide Caption 9 of 58 Photos: Malaysia Airlines Flight 17 crashes in Ukraine An armed pro-Russian rebel stands guard next to a refrigerated train loaded with bodies in Torez, Ukraine, on Sunday, July 20, 2014. Hide Caption 10 of 58 Photos: Malaysia Airlines Flight 17 crashes in Ukraine Ukrainian State Emergency Service employees sort through debris on July 20, 2014, as they work to locate the deceased. Hide Caption 11 of 58 Photos: Malaysia Airlines Flight 17 crashes in Ukraine A woman covers her mouth with a piece of fabric July 20, 2014, to ward off smells from railway cars that reportedly contained passengers' bodies. Hide Caption 12 of 58 Photos: Malaysia Airlines Flight 17 crashes in Ukraine Toys and flowers sit on the charred fuselage of the jet as a memorial on July 20, 2014. Hide Caption 13 of 58 Photos: Malaysia Airlines Flight 17 crashes in Ukraine People search a wheat field for remains in the area of the crash site on July 20, 2014. Hide Caption 14 of 58 Photos: Malaysia Airlines Flight 17 crashes in Ukraine A woman walks among charred debris at the crash site on July 20, 2014. Hide Caption 15 of 58 Photos: Malaysia Airlines Flight 17 crashes in Ukraine Emergency workers load the body of a victim onto a truck at the crash site on Saturday, July 19, 2014. Hide Caption 16 of 58 Photos: Malaysia Airlines Flight 17 crashes in Ukraine Emergency workers carry the body of a victim at the crash site on July 19, 2014. Hide Caption 17 of 58 Photos: Malaysia Airlines Flight 17 crashes in Ukraine A large piece of the main cabin is under guard at the crash site on July 19, 2014. Hide Caption 18 of 58 Photos: Malaysia Airlines Flight 17 crashes in Ukraine Victims' bodies are placed by the side of the road on July 19, 2014, as recovery efforts continue at the crash site. International officials lament the lack of a secured perimeter. Hide Caption 19 of 58 Photos: Malaysia Airlines Flight 17 crashes in Ukraine A man looks through the debris at the crash site on July 19, 2014. Hide Caption 20 of 58 Photos: Malaysia Airlines Flight 17 crashes in Ukraine An envelope bearing the Malaysia Airlines logo is seen at the crash site on July 19, 2014. Hide Caption 21 of 58 Photos: Malaysia Airlines Flight 17 crashes in Ukraine Armed rebels walk past large pieces of the Boeing 777 on July 19, 2014. Hide Caption 22 of 58 Photos: Malaysia Airlines Flight 17 crashes in Ukraine Ukrainian rescue workers walk through a wheat field with a stretcher as they collect the bodies of victims on July 19, 2014. Hide Caption 23 of 58 Photos: Malaysia Airlines Flight 17 crashes in Ukraine A woman looks at wreckage on July 19, 2014. Hide Caption 24 of 58 Photos: Malaysia Airlines Flight 17 crashes in Ukraine Pro-Russian rebels stand guard as the Organization for Security and Co-operation in Europe delegation arrives at the crash site on Friday, July 18, 2014. Hide Caption 25 of 58 Photos: Malaysia Airlines Flight 17 crashes in Ukraine A woman walks through the debris field on July 18, 2014. Hide Caption 26 of 58 Photos: Malaysia Airlines Flight 17 crashes in Ukraine Pro-Russian rebels stand guard at the crash site. Hide Caption 27 of 58 Photos: Malaysia Airlines Flight 17 crashes in Ukraine Wreckage from Flight 17 lies in a field in Shaktarsk, Ukraine, on July 18, 2014. Hide Caption 28 of 58 Photos: Malaysia Airlines Flight 17 crashes in Ukraine A man covers a body with a plastic sheet near the crash site on July 18, 2014. The passengers and crew hailed from all over the world, including Australia, Indonesia, Malaysia, Germany and Canada. Hide Caption 29 of 58 Photos: Malaysia Airlines Flight 17 crashes in Ukraine A diver searches for the jet's flight data recorders on July 18, 2014. Hide Caption 30 of 58 Photos: Malaysia Airlines Flight 17 crashes in Ukraine Coal miners search the crash site. Hide Caption 31 of 58 Photos: Malaysia Airlines Flight 17 crashes in Ukraine Wreckage from the Boeing 777 lies on the ground July 18, 2014. Hide Caption 32 of 58 Photos: Malaysia Airlines Flight 17 crashes in Ukraine People search for bodies of passengers on July 18, 2014. Hide Caption 33 of 58 Photos: Malaysia Airlines Flight 17 crashes in Ukraine A woman walks past a body covered with a plastic sheet near the crash site July 18, 2014. Hide Caption 34 of 58 Photos: Malaysia Airlines Flight 17 crashes in Ukraine Belongings of passengers lie in the grass on July 18, 2014. Hide Caption 35 of 58 Photos: Malaysia Airlines Flight 17 crashes in Ukraine People inspect the crash site on Thursday, July 17, 2014. Hide Caption 36 of 58 Photos: Malaysia Airlines Flight 17 crashes in Ukraine People walk amid the debris at the site of the crash. Hide Caption 37 of 58 Photos: Malaysia Airlines Flight 17 crashes in Ukraine Debris smoulders in a field near the Russian border. Hide Caption 38 of 58 Photos: Malaysia Airlines Flight 17 crashes in Ukraine Fire engines arrive at the crash site. Hide Caption 39 of 58 Photos: Malaysia Airlines Flight 17 crashes in Ukraine A man stands next to wreckage. Hide Caption 40 of 58 Photos: Malaysia Airlines Flight 17 crashes in Ukraine Debris from the crashed jet lies in a field in Ukraine. Hide Caption 41 of 58 Photos: Malaysia Airlines Flight 17 crashes in Ukraine Family members of those aboard Flight 17 leave Schiphol Airport near Amsterdam, Netherlands. Hide Caption 42 of 58 Photos: Malaysia Airlines Flight 17 crashes in Ukraine A large piece of the plane lies on the ground. Hide Caption 43 of 58 Photos: Malaysia Airlines Flight 17 crashes in Ukraine Luggage from the flight sits in a field at the crash site. Hide Caption 44 of 58 Photos: Malaysia Airlines Flight 17 crashes in Ukraine A couple walks to the location at Schiphol Airport where more information would be given regarding the flight. Hide Caption 45 of 58 Photos: Malaysia Airlines Flight 17 crashes in Ukraine Flight arrivals are listed at the Kuala Lumpur International Airport in Sepang, Malaysia. Hide Caption 46 of 58 Photos: Malaysia Airlines Flight 17 crashes in Ukraine Debris from the Boeing 777, pictured on July 17, 2014. Hide Caption 47 of 58 Photos: Malaysia Airlines Flight 17 crashes in Ukraine A man inspects debris from the plane. Hide Caption 48 of 58 Photos: Malaysia Airlines Flight 17 crashes in Ukraine Wreckage from the plane is seen on July 17, 2014. Hide Caption 49 of 58 Photos: Malaysia Airlines Flight 17 crashes in Ukraine A man talks with security at Schiphol Airport on July 17, 2014. Hide Caption 50 of 58 Photos: Malaysia Airlines Flight 17 crashes in Ukraine Wreckage burns in Ukraine. Hide Caption 51 of 58 Photos: Malaysia Airlines Flight 17 crashes in Ukraine A man stands next to the wreckage of the airliner. Hide Caption 52 of 58 Photos: Malaysia Airlines Flight 17 crashes in Ukraine People inspect a piece of wreckage believed to be from Malaysia Airlines Flight 17. This image was posted to Twitter Hide Caption 53 of 58 Photos: Malaysia Airlines Flight 17 crashes in Ukraine People inspect a piece of wreckage believed to be from Malaysia Airlines Flight 17. This image was posted to Twitter. Hide Caption 54 of 58 Photos: Malaysia Airlines Flight 17 crashes in Ukraine A piece of wreckage believed to be from Malaysia Airlines Flight 17. This image was posted to Twitter Hide Caption 55 of 58 Photos: Malaysia Airlines Flight 17 crashes in Ukraine A piece of wreckage believed to be from MH17. This image was posted to Twitter Hide Caption 56 of 58 Photos: Malaysia Airlines Flight 17 crashes in Ukraine An airsickness bag believed to be from MH17. This image was posted to Twitter Hide Caption 57 of 58 Photos: Malaysia Airlines Flight 17 crashes in Ukraine A piece of wreckage believed to be from MH17. This image was posted to Twitter Hide Caption 58 of 58

"All representatives from the states participating in the investigation endorse the conclusion that the crash was caused by the detonation of a warhead in close proximity to the airplane," Joustra said.

"Not all of the representatives endorsed the conclusion that a 9N314M warhead was involved. In its comments on our reports, the Russian Federation states that it is not possible to determine the type of warhead or the type of missile that carried this with certainty."

In an appendix to its main report, the DSB said Russia indicated that MH17 was downed by a missile that could have been fired from either the ground or an airplane.

The Russian manufacturer of Buk missile systems, Almaz-Antey, said its own testing and calculations also threw doubt on the DSB's report, Russia's state-run TASS news agency reported.

Almaz-Antey's CEO said at a news conference Tuesday that the company believed an older warhead, which fitted a missile system now only used by Ukraine's military, had been used, TASS said.

The Russian government on Tuesday argued that the DBS ignored Almaz-Antey's conclusions about the crash, and questioned the transparency of the investigation.

Russian Foreign Ministry spokeswoman Maria Zakharova said the investigation should continue, be corrected, and include "governments that possess materials that could shed light on the catastrophe."

Passengers likely 'barely able to comprehend'

The DSB said that perforation of "pre-formed fragments" had immediately killed three of the plane's crew members after the warhead exploded.

But it said no such fragments were found in other passengers and it was "likely that the occupants were barely able to comprehend the situation in which they found themselves."

"As a result of the impact, they were exposed to extreme and many different, interacting factors: abrupt deceleration and acceleration, decompression and associated mist formation, decrease in oxygen level, extreme cold, strong airflow, the aeroplane's very rapid descent and objects flying around," the board's report said.

"As a result, some occupants suffered serious injuries that were probably fatal. In others, the exposure led to reduced awareness or unconsciousness within a very short time. It was not possible to ascertain at which moment the occupants died. The impact on the ground was not survivable.

"The Dutch Safety Board did not find any indications of conscious actions performed by the occupants after the missile's detonation."

Relatives of the crash victims were informed of the findings ahead of the report's release, the Dutch Safety Board said

Finding those responsible

Ukrainian President Petro Poroshenko commented Tuesday on the results of the investigation.

"The missile was launched from the territory occupied by Russians," Poroshenko alleged in a quote posted to his official website. "Dutch investigators cannot reveal the surnames of criminals. It should be done by the international tribunal."

Also Tuesday, Dutch Prime Minister Mark Rutte said of those who brought down the plane: "We must do the utmost so that the people who did it will not avoid ... punishment."

Rutte added that the investigation has had "an enormous impact" on the Netherlands' relationship with Russia.

"What I would really like to do is to call on the Russian authorities to respect and also give full cooperation to this report and the continued investigation that the criminal prosecutors are doing," he told reporters Tuesday.

The DSB's investigation was not concerned with blame or liability, which falls to a separate criminal investigation lead by Dutch prosecutors and known as the Joint Investigation Team (JIT).

The Dutch prosecutor leading the JIT said its effort would continue into 2016, though he noted the heavy burden in proving a criminal case.

"Ultimately, we have to establish it could have been no other weapon than a Buk and that any other alternatives can be ruled out without any doubt," prosecutor Fred Westerbeke said Tuesday.

Westerbeke said gathering witness accounts from a conflict zone was difficult and time consuming and further forensic investigation was needed to establish exactly where the warhead that downed MH17 had been fired from.

Disputes over responsibility

The disaster and its aftermath -- when armed men initially prevented international monitors from reaching the crash site and recovering the scattered bodies -- shocked the world.

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The greatest loss was suffered by the Netherlands, which had 196 of its citizens on board the flight. Dozens of Malaysians and Australians were also on the plane, as were smaller numbers of UK, Indonesian, Belgian, German, Philippine and Canadian nationals. Disputes over who is responsible have soured relations between Moscow and the West.

Several Western nations and the Ukrainian government have accused pro-Russia separatists operating in the region of shooting down the plane with a missile.

Rebel leaders and the Russian government have repeatedly disputed those allegations, and have suggested instead that Ukrainian forces shot the plane down with either a surface-to-air missile or one of their own fighter jets.

Even before the MH17 disaster, Western nations accused Russia of supplying the rebels in Ukraine. The United States and the European Union imposed sanctions against Russia last year to punish it for this and its annexation of the Ukrainian peninsula of Crimea.