The administration of US President Joe Biden has prepared a set of sanctions against Russia that includes a ban on US financial institutions from processing transactions of major Russian banks, three sources familiar with the matter have said.

The measures, which would only be imposed if Russia invades Ukraine, involve cutting off “correspondent” banking relationships between Russian banks that would fall under the sanctions and U.S. banks that provide international payments.

While U.S. officials have said the banking restrictions would be part of a possible set of sanctions, the administration’s plan to sever correspondent banking relationships – which underpin global money flows – has not been previously reported.

The United States will also place a number of Russian individuals and entities on the sanctions watch list (SDN), the same sources said.

The White House and the U.S. Treasury Department declined to comment.

The sources said the composition of the sanctions could change right up to the last minute, and it is still unclear who will be targeted.

At the same time, the sources believe that Russia’s leading financial institutions, including VTB, Sberbank, VEB and Gazprombank, could fall under the sanctions.