A U.S. threat to hit financial firms doing business with Russia with sanctions has chilled Turkish-Russian trade, disrupting or slowing some payments for both imported oil and Turkish exports, according to seven sources familiar with the matter. The U.S. executive order in December did not explicitly target energy but it has complicated some Turkish payments for Russian crude as well as Russian payments for a broader range of Turkish exports, the sources said. U.S. sanctions aim to reduce the Kremlin's revenue and disrupt its war in Ukraine without choking Russian oil flows to global markets, to avoid a politically sensitive jump in U.S. gasoline prices with President Joe Biden seeking re-election in November.