A group of U.S. senators have sent a letter to the U.S. Treasury asking for tough sanctions to be placed on Russian banks that they suspect of helping to fund the Syrian government's war effort.
The letter was sent to Secretary of the Treasury Jack Lew by senators Richard Blumenthal, Kelly Ayotte, John Cornyn and Jeanna Shaheen, Politico reported Tuesday.
They want to freeze the accounts of Russian banks to stop them doing business in the United States, and to prevent their employees entering America.
Blumenthal, from the Democratic Party, believes that the Syrian government's troops wouldn't be able to keep fighting without support from Russia's banks.
The letter said that banks like VTB, Vneshekonombank and Gazprombank do business with Syria, undermining existing sanctions from the United States, the EU and the UN.
The senators also pointed to the supposed involvement of Vneshekonombank in the fulfillment of payments for the S-300 rocket system, and VTB securing President Assad's personal assets.
The Treasury refused to comment on the letter, but said that the U.S. authorities were already subjecting the Bashar Assad regime to tough sanctions.
The senators' proposal to sanction Russian banks actually came after the U.S. and Russia came to an agreement on a chemical weapons strategy for Syria.
A number of senators and congressmen have already expressed their disapproval of the deal and have called for the U.S. authorities to turn the screw on Russia over its refusal to see eye-to-eye with the West on a number of issues.
The U.S. has accused the Assad regime of carrying out a chemical attack in Damascus in August, but Russia has disputed the claim, saying that insufficient evidence had been provided.