As reported by Censor.NET, this was announced by Assistant Secretary of State Victoria Nuland on Wednesday in a testimony before the House Foreign Affairs Committee.
"In pure economic terms, the price of Russia's air campaign is estimated at $2-4 million per day. This at a time when average Russians are feeling the pinch of a recession brought on by economic mismanagement, low oil prices, and sanctions applied for the Kremlin's last military adventure: Ukraine," Nuland stated.
According to her, "Russian casualties are also reportedly on the rise, although the Kremlin is again working overtime to mask them and silence the loved ones of the lost."
In addition, "Russia is paying a steep price to its reputation in the fight against terror," the representative of the U.S. State Department noted.
"That is why, for now, we have limited our military cooperation with Russia to the most basic aviation de-confliction to protect our own aircrews," the diplomat said.
She stressed that the United States and its allies in the international community are awaiting further evidence that Russia is sincere in its claims to want to fight ISIL, rather than simply protecting the dictator who bears direct responsibility for the country's destruction.
In the meantime, as Nuland said, the U.S. will accelerate the work in support for the moderate Syrian opposition as well as protection of Syria's neighbors including Turkey and the countries of Europe.