The Democratic Party in the US has begun preparations for a possible parliamentary investigation into the agreements between the Donald Trump administration and Moscow on the supply of diesel. American media reports that lawmakers, who could chair key committees if they win the election, have already sent letters to major banks and port authorities demanding that they preserve all documentation related to potential imports of Russian diesel and related transactions. The letters were received by six leading financial institutions -. J. P. Morgan, Bank of America, Citi, Wells Fargo, Goldman Sachs and Morgan Stanley, as well as the Port Authority of Houston, Beaumont and Corpus Christi in Texas and the Port of New York and New Jersey. Signatories include Democratic Senators Gene Shaheen, Chris Coons, Elizabeth Warren, Ron Wyden and Sheldon Whitehouse, as well as Republican Tom Tillis; Congressman Greg Meeks, who may be chairman of the House Foreign Affairs Committee, also signed. The wording of the appeal states that any import of Russian diesel fuel to the US "raises serious legal problems and may be the subject of lawsuits, as well as parliamentary investigations." In addition, the lawmakers point to a threat to national security, as such deals could finance "Russia's brutal and illegal war against Ukraine." Banks and ports are advised to refrain from facilitating the "purchase, transportation, importation, unloading, storage, financing or distribution" of Russian diesel in the United States, as well as from participating in fuel supply transactions in other markets under the recently issued sanctions exemption. Documents to be kept include contracts, bills of lading, vessel records and correspondence with suppliers, brokers and US officials. Confirmation of receipt of the request is expected by Wednesday.