U.S. Department of State Spokesperson Morgan Ortagus says her country continues to "impose costs" on Russia until the Kremlin respects Ukraine's sovereignty and territorial integrity.

"Russian aggression in Ukraine must stop," the State Department spokeswoman tweeted Thursday in response to the call by her Ukrainian counterpart, MFA Ukraine's spox Kateryna Zelenko, for an "international response" to the latest spike of Russian aggression in Donbas, which brought more casualties among Ukrainian troops.

"We will continue to impose costs until Russia respects Ukraine’s sovereignty and territorial integrity," Morgan Ortagus added in the same tweet.

Earlier, Kateryna Zelenko, via Twitter, informed the international community of the latest escalation in eastern Ukraine where Russian hybrid forces attacked Ukrainian positions in Pisky.

"Russia’s hybrid military forces have attacked Ukrainian positions at #Pisky with 2 #Ukrainian soldiers reportedly killed and 9 injured. A united international response is needed in order to #StopRussianAggression. Our thoughts are with the families of our fallen heroes," she tweeted.