By Daphne Psaledakis and Steve Holland
WASHINGTON (Reuters) - The United States on Thursday imposed sanctions on four current and former Ukrainian officials it accuses of working with Russia's intelligence service to destabilize Ukraine as Washington warned it was prepared to take further action if Moscow invaded its neighbor.
Russia has massed tens of thousands of troops on its borders with Ukraine in what Western states fear is the precursor to a new assault on the former Soviet republic. Russia denies it is planning an attack, but says it could take unspecified military action if a list of demands is not met.
"We're not waiting to counter Russia with these actions, we're taking steps now to do so. This demonstrates that we stand with the Ukrainian government in seeking to identify, expose and to undercut Russia's destabilization efforts inside Ukraine," a senior U.S. administration official told reporters.
The United States targeted two members of the Ukrainian parliament, Taras Kozak and Oleh Voloshyn, as well as former officials Volodymyr Oliynyk and Vladimir Sivkovich, the Treasury Department said in a statement.
The statement said the four individuals act at the direction of Russia's FSB security service and have played roles in Russia's campaign to destabilize sovereign countries.
Kozak controls news channels in Ukraine and supported plans to denigrate members of Ukrainian President Volodymyr Zelenskiy's inner circle and falsely accused him of mismanagement, the Treasury said.
It accused Voloshyn of working with Russia to undermine Ukrainian officials.
Kozak and Voloshyn are members of the political party of Viktor Medvedchuk, the Kremlin's most prominent ally in Ukraine who was put under house arrest last year in a treason case.
The party, called the Opposition Platform - For Life, slammed the sanctions as evidence of Washington's "dictatorial approach" in Ukraine, "inciting militaristic hysteria and bold Russophobia."
Oliynyk, who fled Ukraine to Russia, worked with the FSB to gather information about Ukrainian critical infrastructure, while Sivkovich, who is a former National Security and Defense Council official, attempted to build support for Ukraine to officially cede Crimea to Russia, the Treasury said.
'RANGE OF SANCTIONS'
Thursday's action was the latest by Washington to target Russian disinformation and interference, a second senior U.S. administration official said.
"They come in addition to a range of sanctions we are prepared to take with allies and partners to impose severe costs on Russia and its economy if it were to further invade Ukraine in the future," the official said.
Russia wrested the Crimea region off Ukraine while sending troops there in 2014 and it has supported pro-Russian separatists in eastern Ukraine who have been fighting the government in Kyiv since 2014.
Asked if the United States was planning to target Russia's participation in the SWIFT financial system in the event of a Russian invasion of Ukraine, one official said, "We have not taken any options off the table."
Western countries said on Thursday they would be unified in responding strongly to any Russian assault on Ukraine, shifting into damage control after U.S. President Joe Biden suggested there were divisions https://www.reuters.com/world/europe/blinken-says-russian-attack-ukraine-could-come-very-short-notice-2022-01-19 about how to react to a "minor incursion."
(Reporting by Daphne Psaledakis, Steve Holland and Chris Gallagher, additional reporting by Matthias Williams and Natalia Zinets; Editing by Howard Goller and Paul Simao)