By Enas Alashray, Elwely Elwelly and Phil Stewart DUBAI/WASHINGTON, June 10 (Reuters) - Iran's Revolutionary Guards said they had carried out attacks against a U.S. base in Jordan and 21 other targets in the Gulf on Wednesday in retaliation for American strikes around the Strait of Hormuz, Iranian media reported. The clashes mark one of the biggest exchanges in hostilities since the two countries agreed to a ceasefire in April.