Dollar higher after Iran sanctions, loonie drops after US announces tariff increases

NEW YORK, Aug 24 : The U.S. dollar advanced on Monday, coming off its third weekly decline in four that sent the greenback to three-month lows after President Donald Trump's administration announced an expansion of sanctions on Iran and separate tariffs on goods from Canada.The greenback extended gains after U.S. Treasury Secretary Scott Bessent announced the expansion of secondary sanctions in hopes they will "sever every economic lifeline" that sustains Iran in the latest effort to pressure Tehran into ending its attacks on ships in the Gulf. After last week's announcement by the Treasury Department that it would double the size of liquidity support buyback operations for longer-dated notes and bonds, CNBC reported earlier on Monday, citing two senior Treasury officials, that Bessent cou