WASHINGTON — The U.S. State Department said on Sunday pro-Russian militants had seized government buildings in six cities in eastern Ukraine on Saturday in an orchestrated operation reminiscent of those conducted in Crimea before it was annexed by Russia last month.

"Many of the militants were outfitted in bullet-proof vests and camouflage uniforms with insignia removed and carrying Russian-origin weapons," it said in a note entitled "Evidence of Russian Support for Destabilization of Ukraine."

"These operations bear many similarities to those that were carried out in Crimea in late February and culminated in Russia's illegal military intervention and purported annexation of Crimea," the State Department note said.

"The events of April 12 strongly suggest that in eastern Ukraine, Russia is now using the same tactics that it used in Crimea in order to foment separatism, undermine Ukrainian sovereignty, and exercise control over its neighbor in contravention of Russia's obligations under international law," it added.

Earlier on Sunday, the State Department issued a blunt list of what it said were 10 false claims Russia was making in order to justify its operation in Ukraine.