But now experts at the International Institute for Strategic Studies (IISS) in London have told the BBC that they have identified a Russian tank in a separatist column in eastern Ukraine that they say could only have come from across the border in Russia.

Joseph Dempsey, an IISS analyst, has studied video footage reportedly taken on 26 August in Sverdlovsk, Luhansk, in eastern Ukraine. The video shows a convoy of military vehicles.

Whilst date and location are unconfirmed, he says the operator of the convoy is apparent: flags associated with the separatist movement are clearly displayed and some vehicles feature bright green areas, a common feature of separatist armour.

The mixed convoy includes at least three T-72B1 Main Battle Tanks (MBTs) but it is the appearance of a lone, more modern T-72 variant (shown below) that is of particular significance.
A screengrab from the video footage analysed by IISS - 26 August 2014

This variant, distinguished by the prominent Kontakt-5 Explosive Reactive Armour (ERA) arrangement - the boxes on the turret front - is commonly referred to by Western sources as the T-72BM.

It is operated by the Russian Army in large numbers, but crucially it is not known to have been exported or operated outside of Russia.


According to the IISS, the presence of this variant in Ukraine therefore strongly supports the contention that Russia is supplying arms to separatist forces.

Up to now deniability has been a key-note of Moscow's "ambiguous war" strategy in eastern Ukraine.

The IISS says that the first separatist tanks observed were identified as T-64BV, a variant constituting the majority of the Ukrainian army fleet.

It was therefore initially assumed that they, like separatist armoured vehicles before, had been captured in engagements with government forces or through access to known army depots within contested areas.