Oil prices retreated on Tuesday after U.S. President Donald Trump agreed to hold off imposing steep tariffs on Mexico and Canada, the two biggest foreign oil suppliers to the United States, for a month.Brent futures LCOc1 fell 41 cents, or 0.5%, to $75.55 a barrel at 0149 GMT, while U.S. West Texas Intermediate (WTI) crude CLc1 declined 75 cents, or 1%, to trade at $72.41.