July 20 (Reuters) - U.S. gasoline pump prices crossed the $4 a gallon mark on Monday as renewed hostilities between the U.S. and Iran further disrupt energy flows through the Strait of Hormuz, a critical route for global oil supplies.

National average retail gasoline prices have climbed more than 30% since the U.S. and Israel attacked Iran at the end of February. The average pump price on Monday was $4.0030 a gallon, according to data from the American Automobile Association or AAA.