The U.S. has slapped sanctions on two Moscow-backed breakaway regions in the eastern part of Ukraine after Russia formally recognized their independence.

U.S. President Joe Biden issued an executive order on Monday prohibiting new investment, trade and financing by U.S. persons to, from, or in the self-proclaimed Donetsk People’s Republic or Luhansk People’s Republic regions.

White House Press Secretary Jen Psaki said the order will also “provide authority to impose sanctions on any person determined to operate in those areas of Ukraine.”

Psaki said Washington had been prepared for Russia’s move, explaining that the latest measures are separate from severe economic measures the White House has been preparing together with allies and partners should Russia further invade Ukraine.

Biden's executive order is essentially the first sanctions measure the U.S. has taken since the Ukraine crisis first emerged.

The White House is expected to announce further sanctions against Russia on Tuesday.

In a separate statement, U.S. Secretary of State Antony Blinken denounced Russia’s move as a “flagrant disrespect for international law and norms,” adding that the executive order aims to prevent Russia from profiting off of the move.