Earlier in the day, U.S. sailors went aboard the Iran Ajr and found three dead Iranian crewmen, as well as 10 powerful contact-type mines, defense officials said. Ten of the ship's 31 crewmen were plucked from a lifeboat and 16 others from the water, U.S. officials said. Two were missing.
Iran, in its first official comment on the Iran Ajr attack, denied that the vessel was laying mines. Instead, it contended that the ship was loaded with a food cargo when attacked by "U.S. gunship helicopters in the high seas," the Islamic Republic News Agency reported.
Iranian President Sayed Ali Khamenei, speaking before the U.N. General Assembly in New York yesterday, called the U.S. account of Monday's incident a ''pack of lies" and threatened retaliation.
The helicopter attack marked the first time the United States has killed or injured Iranians since the Navy began escorting Kuwaiti tankers through the gulf in July as part of Reagan administration efforts to preserve freedom of navigation in the region in the face of the Iran-Iraq war.
In the gulf yesterday, the frigate Jarrett was towing the Iran Ajr toward Bahrain when an Iranian hovercraft approached it at a high rate of speed. Escorting the Jarrett was the USS LaSalle, command ship of the U.S. fleet in the gulf.
The hovercraft repeatedly called the LaSalle on the radio, saying, "U.S. Navy, U.S. Navy, this is hovercraft, over." But when an Iranian translator on the LaSalle replied - "This is U.S. Navy, hovercraft . . . You are standing into danger. Request you remain clear" - there appeared to be no response
from the Iranian vessel.
The Jarrett then fired two rounds across the bow of the hovercraft, the Pentagon said, adding that "the hovercraft then turned away and stopped."
The hovercraft - which travels above the water on an air cushion at speeds up to 40 m.p.h. - was about 1,000 yards from the frigate when the Jarrett fired, according to a pool reporter on the LaSalle. The craft turned off the air pressure at the sound of the shots and came down onto the water, the Pentagon said.
"It was one way for them to show that there were no bad intentions," one source said. "Possibly they were looking for survivors (from the Iran Ajr). Nothing happened."
The attack on the Iran Ajr was praised by President Reagan and some members of Congress as well as by Prime Minister Margaret Thatcher of Britain.
The President yesterday defended the U.S. action, saying that "we did what was authorized by law." Defense Secretary Caspar W. Weinberger prepared to leave for the Persian Gulf today to visit some of the 20,000 U.S. servicemen in the region. His trip was scheduled well before this week's clashes.
White House spokesman Marlin Fitzwater said yesterday that the United States planned to return the captured crew of the Iran Ajr to Iran as soon as possible, but wanted to keep the ship and its mines as evidence of what is said was Iran's belligerence.
The ship will be anchored in international waters off Bahrain until officials determine its fate, Pentagon officials said. Reports indicated that the captured seamen would eventually be returned to Iran through the Red Crescent, the Islamic version of the Red Cross.
"Our main purpose at this point is to document the laying of the mines," Fitzwater said.
But at the United Nations, Iran's president, Khamenei, denied the accusations and delivered a warning to the United States:
"I unambiguously announce that Washington will receive the appropriate response to its mischievious act," said Khamenei.
He also rejected Reagan's call for an immediate cease-fire in the gulf and blamed the United States, which he called "the arch-Satan," for tensions in the region.
Tehran radio said that the Iran Ajr was attacked while ferrying cargo to the upper gulf and that five crewmen had been killed and four injured.
"America's rulers will be sorry for this crime," the speaker of Iran's Parliament, Ali Akbar Hashemi Rafsanjani, was quoted by the government-run radio network as saying.
Rafsanjani also denied that the ship was laying mines. He said the U.S. Navy should not have attacked the vessel, even if it had been laying mines, and should have limited itself to "sweeping the mines."
In the attack Monday, at least one U.S. helicopter unleashed streams of 7.62mm machine-gun rounds and 2.75-inch rockets at the Iranian ship after the aircraft's crew members - using night-vision devices - detected it laying mines about 50 miles northeast of Bahrain. A second U.S. helicopter was involved in the operation, but it was not clear if it too opened fire.
The assault left "rocket holes in the hull and the stern badly damaged," the Defense Department said yesterday. U.S. forces had monitored the Iranian vessel's movements for days because the Navy suspected it might be laying mines, defense officials said.
Pentagon spokesman Fred Hoffman said the Iranians had deployed six mines
from the Iran Ajr before they were attacked. At least one mine was seen floating on the water's surface, and U.S. helicopters were searching the gulf yesterday to find the others.
The Pentagon said U.S. military men boarded the Iranian ship about seven hours after the attack and found the bodies and mines. "Ten mines and various fuses and pins used in arming the mines were found on the landing craft," a Pentagon official said.
Defense officials said that the mines were similar to the types found previously in the gulf and that despite their primitive design, they could sink most Navy ships.
Three hours later, U.S. forces found and boarded the vessel's lifeboat. Four of the 10 Iranian crew members aboard were wounded and all were taken to the USS LaSalle, which serves as the flagship for the U.S. Middle East Force, along with the 16 Iranians recovered from the water. The three most seriously wounded were taken to the USS Guadalcanal for treatment.
Hoffman said the Jarrett's crew was "quite confident" that the Iranians were laying mines before their helicopters opened fire. "We attempt to be prudent in these things, and so I think they acted properly," he said.
Hoffman said this was not the first time that U.S. forces suspected that the Iranians were laying mines. "But this is the first time that we caught them red-handed," he said.
He said the Navy had photographs of the mine-laying operation, but Adm. William Crowe, chairman of the Joint Chiefs of Staff, told United Press International that the pictures were of poor quality.
Reporters in a Pentagon press pool who visited the Iranian ship yesterday said that there were large gashes in its hull and deck and that it was ''pocketed by machine-gun fire and stained with blood."
Windows on the ship's bridge were shattered, and the ship's living quarters appeared ransacked - suggesting the crew may have tried to locate and destroy incriminating evidence before abandoning the ship.
The black, spiked mines with serial numbers in bold white figures were still on the deck of the 180-foot vessel when the reporters boarded. The ship appeared to be a cargo vessel that had been adapted for military use: Reporters noted two heavy machine guns flanking the ship's bridge.
Meanwhile, during a press briefing on the LaSalle, Rear Adm. Harold J. Bernsen disclosed that the United States had launched two spearate helicopter attacks at the Iran Ajar.
The first attack failed to deter the Iranians, who resumed the mine-laying operation 34 minutes later, Bernsen said.
He said the Iranian ship had been under surveillance before the attack, but declined to say for how long. He refused to rule out the possibility that its movements had been monitored from the time it left port, apparently the Iranian city of Bandar Abbas.
But the admiral said that the ship was tracked by radar before visual contact was established and that the mines were spotted as the crew removed a tarp that had concealed them.
After the attack, he said the Iranian survivors fled the ship after it went dead in the water and boarded a lifeboat and an inflated Zodiac boat, both equipped with motors. The sailors left behind three dead crew members, who had been hit by machine-gun fire.
Windows in the bridge were shattered, rooms ransacked and personal belongings strewn about in the living quarters.
Military sources said there was evidence indicating that documents aboard the ship had been destroyed in the lower decks before the crew abandoned the vessel.
Bernsen said the mines planted by the Iranians appeared to be of the type that damaged the reflagged Kuwaiti-owned tanker Bridgeton on July 24 and the U.S.-owned tanker Texaco Caribbean in the Gulf of Oman last month.
Aboard the Iran Ajr, meanwhile, reporters from a Defense Department pool noticed that cartons of Winston cigarettes were left behind in the crew quarters, clothing was strewn about on unmade cots and a shattered pair of eyeglasses lay on the floor.
At least 11 large bullet holes had ripped through the bulkhead of the captain's quarters, where an empty briefcase was left behind. The captain's copy of Jane's Fighting Ships, 1981 to 1982, lay on the floor of his cabin, while books on international maritime law had been left undisturbed on an overhead bookcase.