KIEV, Ukraine (CNN) -- As bodies from Thursday's air disaster reached a facility Tuesday in Kharkiv, Ukraine, the Ukrainian government ratcheted up its accusations against Moscow, saying a Russian officer shot down Malaysia Airlines Flight 17.
Vitaly Nayda, Ukraine's director of informational security, made the accusation in an interview with CNN. It was a "Russian-trained, well-equipped, well-educated officer" who "pushed that button deliberately," he said.
Ukrainian intelligence backs up the assertion, Nayda said.
Moscow has denied claims that it pulled the trigger. And Russian Army Lt. Gen. Andrei Kartapolov suggested a Ukrainian jet fighter may have shot the plane down.
Ukrainian President Petro Poroshenko rejected that in an exclusive interview with CNN, saying that all Ukrainian aircraft were on the ground at the time.
Nayda, speaking to CNN on Tuesday, referred to audio recordings captured by Ukrainian intelligence. "We taped conversations" between a Russian officer and his office in Moscow, Nayda said. "We know for sure that several minutes before the missile was launched, there was a report" to a Russian officer that the plane was coming, Nayda said.
"They knew the plane was coming with constant speed, in constant direction," and should have known it was not a fighter jet but "a big civilian plane," he said.
That recording is not among those that have been released.
Vitaly Churkin, Russia's ambassador to the United Nations, was asked Monday about different intercepted recordings, purportedly of pro-Russian rebels talking about shooting down a plane. Churkin suggested that if they did, it was an accident.
"According to them, the people from the east were saying that they shot down a military jet," he said. "If they think they shot down a military jet, it was confusion. If it was confusion, it was not an act of terrorism."
Pro-Russian rebels have repeatedly denied responsibility for the attack.
"This is an information war," rebel leader Alexander Borodai said. "We don't have the technical ability to destroy this plane. Ukrainians are not interested in the truth."
U.S. intelligence analysts are examining phone intercepts, social media posts and information gathered on the ground to see whether Russian officials played a direct role in the shootdown, according to two U.S. officials directly familiar with the assessment. The officials declined to be identified because of the sensitivity of the situation.
Dutch PM: Identifying bodies could take months
Bodies from the crash were transported to Kharkiv on Tuesday. There were 298 people on board; officials say remains of 282 have been recovered. Ukraine has also said 87 "body fragments" were recovered from the sprawling crash site, but it's unclear whom they belonged to.
The bodies were transferred to a local factory, where a facility has been set up to transfer remains to coffins and get them on a military plane to the Netherlands for forensic investigation.
Dutch Prime Minister Mark Rutte said Tuesday that he expects the first plane carrying the remains to arrive Wednesday in Eindhoven.
As soon as the remains are identified, families of the victims will be informed. In some cases, that could happen quickly, Rutte said, but in some cases, identification could take weeks or even months.
Dutch Foreign Minister Frans Timmermans said bringing the victims' remains home is his country's top priority.
"To my dying day, I will not understand that it took so much time for the rescue workers to be allowed to do their difficult jobs," he told the U.N. Security Council on Monday, "and that human remains should be used in a political game."
The 'black boxes'
Ukrainian rebels gave Malaysian officials the data recorders from downed Flight 17 on Tuesday after days of attempts by the Malaysian government.
"In recent days, we have been working behind the scenes to establish contact with those in charge of the MH17 crash site," Malaysian Prime Minister Najib Razak said early Tuesday morning.
Najib said he spoke with Borodai and reached an agreement for the transfer of the "black boxes."
Malaysian officials will keep the black boxes while an international investigation team is being formalized, Najib said.
Once the team is finalized, "we will pass the black boxes to the international investigation team for further analysis," he said.
The voice recorder could include audio from the cockpit, which would show whether the pilots knew the plane had been hit, said Mary Schiavo, a CNN aviation analyst and former inspector general for the U.S. Department of Transportation.
And the flight data recorder will give investigators information about engine settings, pressurization and electronic communications, among other details, she said.
But even the black boxes might not answer the two most pressing questions: who shot down the plane, and why.
The blame game
The U.N. Security Council adopted a resolution Monday demanding full access to the crash site and condemning the downing of the plane.
resolution won unanimous approval from the 15-member council, which includes Russia. It did not specify who was responsible for the crash.
U.S. and other officials have said it appears the plane was shot down by a sophisticated surface-to-air missile in rebel-held territory. Evidence supporting that conclusion includes telephone intercepts and video of a Buk missile launcher traveling into Russia with at least one missile missing.
Obama, British Prime Minister David Cameron and others have said the pro-Russian rebels could not have shot down such a high-flying jet without weapons and training from Russia.
Obama called on Russia to rein in the rebel fighters, who he said had treated remains poorly and removed evidence from the site. "What exactly are they trying to hide?" he said.
CNN's Kyung Lah reported from Kiev; Josh Levs and Holly Yan reported from Atlanta; and CNN's Nick Paton Walsh, Catherine E. Shoichet, Carol Jordan, Pamela Boykoff, Phil Black, Gul Tuysuz, Elizabeth Joseph, Stephanie Halasz, Antonia Mortensen, Barbara Starr and journalist Victoria Butenko contributed to this report.
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