With American warships looking on, Iran began its first military maneuvers in the Persian Gulf since naval clashes last month with the United States and used the occasion to threaten ships bound for Iraq.

The maneuvers began Sunday as the U.S. military inspected the torn wreckage of a Marine Corps AH-1 helicopter pulled from the Persian Gulf a day earlier. The gunship and its two crewmen were lost during the U.S.-Iranian clashes April 18.A military source in the gulf said the fragmentary state of the wreckage indicated the helicopter had been hit by an Iranian missile.

The bodies of the two pilots were recovered May 15.

Army, navy and air force units of the regular Iranian armed forces began the combined maneuvers in the southern gulf, the Sea of Oman and the Indian Ocean "to display (their) combat readiness to guard the marine borders of the country," said Tehran Radio, monitored in Athens, Greece.

The commander of Iran's southern Charbahar naval base said more than 50 vessels from the Iranian navy were taking part in the weeklong exercise, code-named "Zulfiqar," after the sword of Prophet Mohammed's son-in-law.

The Iranian Navy is in a "high state of readiness," said the Iranian commander. "We shall not retreat . . . we shall protect the ships of the Islamic Republic in the Persian Gulf."