Washington - The US State Department on Monday released images provided by Ukraine which it says proves armed separatists in eastern Ukraine are actually Russian military or intelligence officers.
It is the latest attempt by the US to disprove Moscow's claims that it has nothing to do with pro-Russian separatists.
State Department spokeswoman Jen Psaki said as well as those from the Ukrainian authorities, images widely available in the international press or on Twitter indicate the men are Russian forces.
They "show either individuals or signs of a connection with... between Russia and some of the armed militants in eastern Ukraine," said Psaki.
"So these are just further evidence of the connection between Russia and the armed militants," she added.
A series of photos provided by Ukraine to Washington through the Organisation for Security and Co-Operation in Europe (OSCE) shows an image taken in Georgia in 2008 of a man with a distinctive long red beard wearing the insignia of a Russian special forces unit.
The same man with the beard a little greyer is seen in a photo taken at the recent capture of a police station in the Ukrainian town of Kramatorsk by separatist militants, and again in Slavyansk on 14 April, according to the photos provided.
Another series of images, some taken in Crimea, appear to show the same man once more, while more images from Slavyansk show men carrying the same kind of RPG-26 rocket launchers that are issued to Russian troops.
On his official blog, General Philip Breedlove, Nato's Supreme Allied Commander in Europe, outlines why he believes it is clear they are Russian forces.
Among the examples he gives: "The weapons and equipment they carry are primarily Russian army issue. This is not the kind of equipment that civilians would be likely to be able to get their hands on in large numbers."