KHARKIV, Ukraine -- A train bearing the dead from the downed Malaysian airliner finally reached Ukrainian government-held territory Tuesday, but the pro-Russian separatists in control of the crash site showed little willingness to allow the full-scale investigation demanded by world leaders.
Five days after the plane was blown out of the sky, refrigerated railcars bearing victims' bodies -- gathered up after several days in the sun -- rolled out of the war zone and into a weedy railyard in the city of Kharkiv.
The dead will be flown to the Netherlands, the homeland of most of the victims, for identification.
The Dutch government declared Wednesday a day of national mourning as the country prepared for the arrival of the first bodies in the afternoon.
It was unclear how many of the 282 corpses reported found so far were on the train. The crash killed all 298 people aboard Malaysia Airlines Flight 17.
Jan Tuinder, the Dutch official in charge of the international team dealing with the dead, said that at least 200 bodies were aboard the train and that more remains could be found once the body bags are examined fully.
In other developments Tuesday:
• Senior U.S. intelligence officials said they have no evidence so far of direct Russian government involvement in the shooting down of the jumbo jet, which investigators believe was destroyed by a missile fired by separatists. The officials, who briefed reporters on condition of anonymity, said the most likely explanation was that the plane was shot down by mistake.
• In Brussels, the European Union spared Russia sweeping new sanctions for now. The 28-nation bloc imposed punitive measures against Russian individuals but didn't target entire sectors of the economy, preferring to wait for a clearer picture of last week's disaster and Moscow's suspected role.
The release of the bodies came amid other indications of progress: The black boxes were handed over to Malaysia Airlines, and three airline investigators were given access to the site Tuesday.
Still, there was no sign of a full investigation, and it was unclear when one could take place.
Rebel leader Andrei Purgin, deputy prime minister of the self-proclaimed Donetsk People's Republic, was quoted by Russia's Interfax news agency as saying the insurgents are willing to guarantee the security of all international experts. It was not clear if that meant the unfettered access world leaders are demanding.
The wreckage lay unguarded across a wide stretch of farmland in the rebel-held east, raising fears that the evidence has been compromised. Even the red-and-white tape that had sealed off the fields had been torn away.
International observers, who have been allowed visit only when accompanied by armed separatists, warned there were signs that the debris was being mishandled or even tampered with.
After a 17-hour journey from the town of Torez in rebel territory, the train carrying the dead arrived at a Kharkiv factory where Ukrainian authorities have set up their crash investigation center.
The train gave a low-pitched blast from its horn as the gray corrugated refrigerator cars slowly rolled past.
Dutch Prime Minister Mark Rutte warned grieving families that the identification of some victims could take weeks or even months.
Separately, the flight data recorders will be examined by British air accident investigators.
At the crash zone, Malaysia Airlines officials walked the site wearing backpacks, photographing the scattered debris.
Michael Bociurkiw, a spokesman for the Organization for Security and Cooperation in Europe, said observers will check to see whether the wreckage has been disturbed.
"We are keeping a very close eye on that -- looking at the fuselage now compared to what it was on Day One," he said. "And we have noted some differences."
In Moscow, Russian President Vladimir Putin said Russia would do "everything in its power" to facilitate the investigation, including putting pressure on the rebels.
But he said that "was not enough" to resolve the situation. He challenged the legitimacy of the Ukrainian government, saying, "People came to power in an armed, anti-constitutional way."
In Brussels, EU foreign ministers urged Russia to use its influence over the rebels to ensure an independent investigation. In a statement, they said they want "all those in the area to preserve the crash site intact."
The EU targeted more Russian officials with economic sanctions and travel bans. The ministers stopped there for now but asked the EU's executive arm to draw up more sweeping measures by Thursday if Russia fails to cooperate.
Those sanctions would target Russia's high-tech, energy and weapons industries.
"Russia has not done enough to contribute to a de-escalation of the conflict," German Foreign Minister Frank-Walter Steinmeier said.
The EU is Russia's biggest trading partner, and some members are wary of doing too much to antagonize Moscow.
The euro fell to its lowest point this year against the dollar amid fear the downing of the jet will further damage EU-Russia relations.
Lithuanian Foreign Minister Linas Linkevicius blamed "terrorists supplied by Moscow" for shooting down the airliner. He called for an arms embargo in a direct challenge to France, which is building two warships for Russia.