The timing of the memo also could be aimed at dissuading Russia from further military posturing. The Pentagon said just days ago that the movement of Russian heavy-caliber artillery systems across its border into Ukraine was "imminent."
Russian officials have denied allegations of Russia's involvement in eastern Ukraine. Secretary of State John Kerry spoke on Sunday with Russian Foreign Minister Sergei Lavrov, but details about their discussion have not yet been released by the State Department.
The U.S. images claim to 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 seven miles.
The memo said one image provides evidence that Russian forces have "fired across the border at Ukrainian military forces and that Russian-backed separatists have used heavy artillery provided by Russia in attacks on Ukrainian forces from inside Ukraine."
Another satellite image depicted in the memo shows "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 wide areas of impact near the Ukrainian military units indicates fire from multiple rocket launchers," the memo said.
Moreover, the memo included a satellite image that it stated is evidence of self-propelled artillery only found in Russian military units "on the Russian side of the border oriented in the direction of a Ukrainian military unit within Ukraine."
Tensions have run high in that region since Russia seized Crimea in March and Washington has been highly critical of Russian President Vladimir Putin's behavior.
More recently, U.S. intelligence officials have said they have what they call a solid circumstantial case that Russian-backed separatists in Eastern Ukraine are responsible for downing the Malaysia Airlines plane. Citing satellite imagery, intercepted conversations and social media postings, officials say a Russian-made SA-11 surface-to-air missile hit the plane on July 17.
Moscow angrily denies any involvement in the attack.
U.S. officials said they still don't know who fired the missile or whether Russian military officers were present when it happened. But until Sunday, they were unwilling to share evidence that the separatists had the technology to down a plane.
Associated Press writer Philip Elliott contributed to this report.