Ukraine said on Wednesday a rebel who organised the trailer carrying the missile that shot down a Malaysian airliner in 2014, had been captured two years ago and was now serving a sentence in Ukraine.
Malaysia Airlines Flight MH17 from Amsterdam to Kuala Lumpur was shot out of the sky over eastern Ukraine during a rebellion by Russian-backed separatists, killing all 298 people on board. A Dutch-led team of investigators has blamed Russia for supplying the surface-to-air missile that shot it down.
The incident was the deadliest in a war between Russian-backed rebels and Ukrainian forces that has killed 13,000 people. Major fighting ended with a peace deal in 2015, although deadly clashes still occur.
On the fifth anniversary of the incident, Vitaly Mayakov, an official of Ukraine's SBU security service, said the rebel who organized the trailer that brought the missile into Ukraine had been caught two years ago and was now serving a sentence in Ukraine.
"We determined whom this trailer belongs to. We identified the individual from among the fighters who picked it up from the trucking company in Donetsk," Mayakov told a news conference.
"Three years later we managed to detain this person while he was crossing the border from the Russian Federation to the government-controlled territory, unaware of the fact that we suspected him. He is now serving a sentence here, in Ukraine."
He did not identify the individual or explain why this information was not announced earlier.
Mayakov said that more than 150 people involved in transporting the missile launcher to and from Ukraine had been identified.
The Dutch-led international team has named four suspects for the attack on the plane: three Russians and a Ukrainian.
Dutch authorities said Russia has not cooperated with the inquiry and is not expected to surrender defendants. The Russian Foreign Ministry denied that it had not cooperated, while saying on Wednesday the investigation was intended to damage Moscow's reputation.