"The Kremlin has sent hundreds of military to Ukraine, gathered thousands at the border, and provides its puppets in the east (of Ukraine - ed.) with weapons and tanks in unlimited quantities. This is not an assumption, it's a fact," the minister wrote.
According to him, the Western governments have irrefutable evidence of regular deliveries of weapons, as well as the participation of the Russian troops in combats in the Donbas.
"We have satellite pictures at our disposal, photos from people on-sight, the OSCE mission reports and the eyewitness accounts. Russia's attempts to refute this just do not have any credibility," he says.
Against this background, Lidington addresses the preservation of the country's integrity to be the "greatest challenge" for Kyiv.
The British minister's op-ed also contains recognition of European prospects in Ukraine.