Militants were preparing for the invasion of the Russian armed forces into the territory of Ukraine, which was to follow the planned terrorist attack on an airliner in Donetsk region on July 17-18, Chairman of the Security Service of Ukraine Valentyn Nalyvaichenko has said.

"With the permission of the investigation, we also argue and clearly say that it was on July 17 and July 18 that the terrorist leaders expected the invasion of the armed forces of the Russian Federation. It was on July 18 they had planned the military intervention and the assistance to the foreign occupation troops in Luhansk and Donetsk regions," he said at a briefing in Kyiv on Thursday.

According to him, Russian special services and Russian media were preparing the grounds for reports of the alleged shelling of the Russian Federation from the Ukrainian territory.

"It was after the failed terrorist attack that the head of the terrorists, Bezler (Igor Bezler, a Russian citizen, one of the leaders of the self-proclaimed Donetsk People's Republic) one of was summoned to the Russian Federation. We demand the interrogation of those who summoned this man, and of him personally to learn what he reported, what Russian special services told him," Nalyvaichenko said.