The White House on Saturday warned Russia and President Vladimir Putin against further military incursion in Ukraine, amid reports of armed separatists seizing government offices in the eastern city of Slaviansk.

In a statement, White House National Security Council spokeswoman Laura Lucas Magnuson said the situation was reminiscent of the lead-up to Russia's eventual annexation of Crimea.

"We are very concerned by the concerted campaign we see underway in eastern Ukraine today by pro-Russian separatists, apparently with support from Russia, who are inciting violence and sabotage and seeking to undermine and destabilize the Ukrainian state," she said.

"We saw similar so-called protest activities in Crimea before Russia’s purported annexation. We call on President Putin and his government to cease all efforts to destabilize Ukraine, and we caution against further military intervention. We will continue to monitor the situation closely."

Ukrainian Interior Minister Arsen Avakov accused Russia of "aggression" Saturday after separatists reportedly seized government buildings in the cities of Donetsk and Slovyansk. Unrest has been growing in eastern Ukraine over the past week.

Slovyansk's mayor said the men who seized a police station there had demanded a referendum on autonomy and possible annexation by Russia — much like what happened in Crimea.



The White House also said Saturday that Vice President Joe Biden will travel to Ukraine Tuesday for meetings with government leaders and members of civil society.