Senate Majority Leader Harry Reid (D-Nev.) accused Russian President Vladimir Putin of encouraging "neo-Nazi thugs" in eastern Ukraine.
News sources have reported that Jews in eastern Ukraine are being asked to register all of their property and pay a fee. Leaflets have been distributed that say all citizens of Jewish descent 16 years and older had to report to officials in Donetsk, Ukraine, or face deportation.
"No one of any religion should be treated differently, let alone be forced to register with the government based on their religious views," Reid said. "This is a chilling and deeply disturbing echo of one of the darkest periods in human history, and Russia should know that we are watching."
Sen. Charles Schumer (D-N.Y.) called on Putin to denounce the "anti-Semitic" actions.
"President Putin has accused the Ukrainians recently of being anti-Semitic, but now it is pro-Russian forces that are engaged in these grotesque acts," Schumer said. "President Putin should strongly denounce these acts and if he is truly sincere, he has the influence to stop them.
"We have seen this horror movie before, and we're not going to abide by it."
The U.S. has broadly accused Russia of trying to exert its influence in eastern Ukraine, and Russia has already annexed Crimea. Earlier this week, the U.S., Russia and other countries reached a deal aimed at tamping down pro-Russian separatist forces in Ukraine.