A US Navy ship fired warning shots at an Iranian Revolutionary Guards boat at the northern end of the Persian Gulf when it came to within 150 meters and failed to respond to warnings, including radio calls, flares and short whistle blasts. The warning shots prevented a collision but the Iranian boat after withdrawing stayed in the area for some hours. The incident occurred Tuesday. DEBKAfile: The Rev Guards operate fast boats in Gulf waters armed with torpedoes and some packed with explosives. Their crews are training for confrontation with American warships.