By Mick Krever, CNN

Russia cannot continue to pledge its support to deescalating unrest in Ukraine and at the same time fuel that turmoil, the U.S. says.

“You cannot dress yourself like a firefighter and behave like an arsonist,” Victoria Nuland, the top U.S. diplomat for Europe, told CNN’s Christiane Amanpour in an exclusive interview.

“We are very concerned about the Russian hand behind the destabilizing things that we’re seeing in eastern Ukraine.”

A dossier obtained Monday by CNN shows what Ukrainian officials say are images of well-equipped gunmen operating in eastern Ukraine who look similar to photographs of Russian forces taken in Crimea, Russia and during Russia's 2008 invasion of Georgia.

Nuland said that the “bearded man” who has allegedly appeared both in Georgia and eastern Ukraine is “clearly a GRU agent,” referring to the main intelligence body of the Russian military.

CNN cannot independently confirm the photographs, some of which were first published in the New York Times.

U.S. point person on Ukraine crisis Click to watch video

The revelations follow reporting last week by CNN's Arwa Damon citing Ukrainian security officials as saying they had arrested a Russian military officer and a woman Ukrainian officials say is a Russian intelligence agent.

Nuland said that Russia has not been holding up its end of the bargain of an agreement signed last week between Russia, the U.S., Europe, and Ukraine to deescalate the situation in eastern Ukraine.

“We have not seen the kind of major de-escalation that we’re looking for, nor have we seen serious Russian efforts to help the OSCE [Organization for Security and Co-operation in Europe] or to speak out against separatists since Geneva.”

In an interview with Amanpour last week, a key Putin ally singled out Nuland herself for fomenting unrest in Ukraine.

“Victoria Nuland said about five billion U.S. dollars [was] spent to promote democracy in Ukraine, which is oftentimes a code word for regime change,” Vyacheslav Nikonov said.

Nuland acknowledged that American had “invested” $5 billion in Ukraine since the fall of the Soviet Union in 1991.

“That money has been spent on supporting the aspirations of the Ukrainian people to have a strong, democratic government that represents their interests,” she said.

“But we certainly didn’t spend any money supporting the Maidan. That was a spontaneous movement, which is a far cry from what we are concerned Russia is up to now in eastern Ukraine.”

She praised the acting Ukrainian government for fulfilling the two tasks they were given, as she saw them.

“The first was to try to negotiate a deal with the IMF, where they would institute real reform and try to turn the page on the age of corruption that had been rampant in Ukraine.”

“And they have now successfully inked a deal with the IMF; they’ve also passed a vast amount of reform legislation, including to tackle corruption.”

The second task, she told Amanpour, was to hold “free and fair elections.”

“Presidential elections are scheduled for May 25th. There are some 20 candidates registered in those elections, representing all parts of the spectrum.”

The government, she said, is “doing very well” on those two fronts.

But as unrest rears its head in eastern Ukraine, she said, “they also have to ensure that the country is peaceful enough for those elections to go forward.”