The Russian Defence Ministry yesterday cast doubt on pictures that Washington said showed Russia had recently shelled Ukrainian military positions.
The United States has accused Russia of instigating the conflict in eastern Ukraine where pro-Moscow separatists are fighting central government forces. Russia has denied any involvement in the conflict.
On Sunday, the US State Department released images it said showed Russian forces had fired across the border at the Ukrainian military.
Defence Ministry spokesman Igor Konashenkov questioned the substance of the images, according to RIA Novosti news agency. "Such materials weren't posted on Twitter coincidentally, since it's impossible to establish their authenticity due to the lack of exact reference to the location and the extremely low resolution," he said.
The US said the images showed marks on the ground at launch sites and impact craters around Ukrainian military locations, and indicated fire from multiple rocket launchers.
Officials said the images showed heavy weapons fired between July 21 and July 26 - after the July 17 downing of Malaysia Airlines Flight 17 over Ukraine.
The four-page memo is part of the Obama administration's push to hold Russia accountable for its activities in neighbouring Ukraine and persuade its European allies to apply harsher sanctions on Russia.
The timing of the memo could also be aimed at dissuading Russia from military posturing.
Russia's foreign ministry over the weekend accused the US of "an unrelenting campaign of slander against Russia, ever more relying on open lies".
US Secretary of State John Kerry spoke by phone on Sunday with Russian Foreign Minister Sergey Lavrov, urging him to stop the flow of heavy weapons and rocket and artillery fire from Russia into Ukraine, a State Department official said. Kerry did not accept Lavrov's denial that heavy weapons from Russia were contributing to the conflict.
The US claims its images show multiple rocket launchers fired at Ukrainian forces from within Ukraine and from Russian soil. One image shows dozens of craters around a Ukrainian military unit and rockets that can travel more than 11km.
The memo said one image showed that Russian forces had "fired across the border at Ukrainian military forces and that Russian-backed separatists used heavy artillery provided by Russia in attacks on Ukrainian forces from inside Ukraine".
Another satellite image depicted in the memo showed "ground scarring at multiple rocket launch sites on the Russian side of the border oriented in the direction of Ukraine military units within Ukraine".
The memo said: "The wide areas of impact near the Ukrainian military units indicates fire from multiple rocket launchers."