MH17 was shot down by a surface-to-air missile at 4:20 p.m. on Thursday.
In the intercepted phone call between two militants, identified as "Major" and "Greek," Major reports at 4:33 p.m. local time on Thursday that a civilian plane was shot down, confirming multiple times that it was not a military flight.
"The plane was shot down by those who are the Chornukhyne roadblock [in Luhansk region] ... The Cossacks who are Chornukhyne. The plane has fallen apart in the air, near the Petropavlivska mine. We've found the first 'Cargo 200' (corpse). It was a woman. It's a civil [aircraft]."
Then, at 5:42 p.m., Major again confirms the plane was civilian, not military.
"In short, it's set in stone it's a civil plane."
Greek asks whether any military equipment was found at the crash site.
Major responds: "Nothing at all. Civilian stuff, medical scraps, towels, toilet paper."
Twenty minutes after the plane was shot down, the SBU revealed that Igor Bezler, a Russian citizen and rebel leader in the Ukrainian eastern town of Gorlovka, called Vasily Geranin, Colonel of the Main Intelligence Directorate of the General Staff of the Russian Armed Forces.
At 4:40 p.m. local time, Bezler reported to Gernanin:
"A plane has just been shot down. [It has been shot down by] a 'Miner' group. Near Yenakiyeve ... They left to search for the downed plane and take photos of it. There's smoke."
Geranin asks "how many minutes ago [did it happen]?"
Bezler responds: "About 30 minutes ago."
According to a New York Times translation of the intercepted phone call, Bezler claims that his men had "shot down a plane."
SBU Chief Valentyn Nalyvaichenko said at a press conference in Kiev late Thursday that the intercepts prove Russian involvement in the downing of Malaysia Airlines Flight 17.
"Now you know who carried out the crime. We will do everything to ensure that those Russian soldiers who carried out this crime were punished."
283 passengers and 15 crew members were aboard MH17 when it crashed in eastern Ukraine en route from Amsterdam to Kuala Lumpur.