The head of the Ukrainian president’s office says that Volodymyr Zelenskiy’s administration will do “everything in its power to hold…responsible” Ukrainians who meddled in the November U.S. election after Washington imposed sanctions on nearly a dozen Ukrainian nationals and entities.

“For the sake of clarity — regardless of party affiliation, this administration will do everything in its power to hold [to account] those responsible for meddling in U.S. elections,” Andriy Yermak tweeted.

The U.S. Treasury on January 11 accused seven individuals and four entities of involvement in a Russian-linked foreign-influence network associated with Ukrainian parliament member Andriy Derkach.

Derkach was put under U.S. sanctions in September over alleged efforts to influence the presidential vote, which was won by Democratic challenger Joe Biden.

He has reportedly promoted unproven allegations — circulated within Republican supporters — that Biden’s son Hunter improperly used his influence with his father to block a Ukrainian investigation into energy company Burisma, on whose board the younger Biden sat.

Derkach has said the sanctions are punishment for exposing corruption.

One of the individuals added to the Specially Designated Nationals (SDN) list at the Office of Foreign Assets Control on January 11 is Oleksandr Dubinskiy, from Zelenskiy’s ruling Servant of the People party.

People and entities on the SDN list have their U.S. assets blocked and U.S. nationals are generally prohibited from dealing with them.

With reporting by Reuters