The Trump administration is reportedly considering new sanctions targeting Russia’s so-called “shadow fleet” of oil tankers if President Vladimir Putin fails to agree to a ceasefire in Ukraine by Friday, according to a report by the Financial Times on Tuesday. The move would mark a significant escalation in the U.S. effort to restrict Russia’s oil export revenues, which remain a critical source of funding for the Kremlin’s military operations. Russia’s so-called “shadow fleet” is a loose collection…