A US Navy ship fired warning shots at an armed Iranian patrol boat Tuesday in the northern end of the Persian Gulf, according to two US defense officials.

The Iranian boat is believed to have been operated by the Iranian Revolutionary Guard Corps, according to a defense official familiar with details of the incident. The officials said the Iranian boat approached and came within 150 yards of the US ship.

The Iranians did not respond to any warnings from the US ship, including radio calls, firing of flares and five short blasts from the US Navy ship's whistle, which is the internationally recognized communications signal for danger, the officials said.

The Navy ship then fired warning shots into the water over concerns about the possibility of a collision, one of the officials said.

The Iranian ship then ceased its provocative actions but lingered in the area for some hours, one of the officials said. There were several US Navy ships in the immediate vicinity at the time of the incident conducting routine patrol operations in international waters, according to the defense officials.