 And Russian executive bankers and former senior U.S. sanctions officials say the most powerful measure against Russia, if it's where to invade Ukraine, will be U.S. sanctions, cutting off Russian state banks from the dollar. The United States has warned that Russia could invade as early as this week, but Moscow has denied it has such plans but says the West needs to take its concerns about NATO expansion seriously. U.S. and European officials say Washington and its allies in Europe are finalizing an extensive package of sanctions if Russia were to launch an invasion.