B-52 Goes Down in Ocean; 6 Dead in Copter Crashes : Gulf War: Mechanical failure blamed in loss of bomber that was returning from a mission. U.S. says eight Marines killed last week were victims of allied fire.

Six U.S. helicopter crewmen were killed in two separate crashes, and three airmen were reported missing after their B-52 crashed into the Indian Ocean while returning from a bombing run over Iraq, U.S. military officials said Sunday.

Also Sunday, Marine officials said seven of the 11 Leathernecks killed in a light armored vehicle last week and another Marine killed in a cluster-bomb attack Saturday were victims of so-called friendly fire.

All four crew members died in the crash of a Marine UH-1 helicopter on a noncombat mission in eastern Saudi Arabia, the U.S. Central Command said. No other details of the crash were immediately available.

In a second crash, two Cobra helicopter crewmen were killed when their gunship went down during an escort mission inside Saudi Arabia, officials said.

Three crew members were rescued from the B-52, which crashed late Saturday while on its way back to its base on the Indian Ocean island of Diego Garcia, 2,000 miles southeast of the Persian Gulf. Military investigators said there was no evidence that the crash of the eight-engine, $55-million Stratofortress was due to hostile fire, and they tentatively attributed it to mechanical failure.

The deaths of the six helicopter crewmen increased the number of servicemen killed since the war began to 18, while the missing B-52 crewmen raised the total of American missing to 26.

The crashes came as allied airmen flew more than 2,500 missions Sunday, concentrating almost exclusively on ground targets now that the U.S.-led coalition has claimed superiority in the air over Iraq and Kuwait and the waters of the Persian Gulf. A major target Sunday, as it has been for days now, was Iraq’s crack Republican Guard, which was pounded with tons of explosives in round-the-clock bombing runs.

In other developments:

* State-run radio in neighboring Iran reported that allied air strikes on eastern Iraq on Sunday had produced a “horrific explosion” so powerful it sent shock waves into the border areas of western Iran. “The roar of aircraft over Iraq could be heard all night from afar,” said the broadcast, monitored in Jordan.

* Syrian and American officials denied an Iraqi radio report that Syria had turned over to U.S. officials in Damascus seven American pilots who were said to have parachuted into Syrian territory after their planes were shot down by Iraqi forces.

* Iraq threatened Sunday to hit American and Western targets worldwide in retaliation for alleged allied air attacks on civilian targets.

* Former attorney general and peace activist Ramsey Clark arrived in Baghdad on Sunday. He met with Foreign Ministry officials and said he expected to meet with Iraqi President Saddam Hussein.

* Secretary of Defense Dick Cheney said he opposes the use of nuclear weapons against Iraq, but an Iraqi diplomat would not rule out the use of chemical or biological weapons against allied forces.

Friendly Fire

Marine Maj. Gen. Robert Johnston of the U.S. Central Command said Sunday that evidence pointed conclusively to the assessment that seven of 11 Marines killed last week in a light armored vehicle during a clash with Iraqi forces were the victims of friendly fire. The missile that hit their transport entered the rear left-hand side during the fierce engagement with Iraqi tanks and armored personnel carriers, the general said.

“What I’m describing for you is a very intense, very close combat,” Johnston said. Describing the damage to the vehicle, he said, “We have every reason to conclude that it was a (U.S.) Maverick missile” that struck it.

He also said it seemed certain that a Marine who was killed Saturday in a cluster-bomb attack on a U.S. convoy was a victim of friendly fire.

“That was in a convoy well inside the border and, again, because of its lack of proximity to enemy fire, it would appear reasonable to expect that that, too, could have been friendly fire.”

The deaths of the Marines can be blamed in large measure on the fact that air and land forces are operating around the clock and it is much easier to misidentify a target in the dark, said Lt. Gen. Charles A. Horner, commander of U.S. air forces in the Persian Gulf.

“Before, we tended (to use) air (power) during daylight, when it was much easier to make sure that the target you were looking at was in fact an enemy target,” Horner said in an interview with Cable News Network.

Calling the Marine deaths “a failure of the procedures you have set up to preclude this from happening,” Horner added: “The specifics of these particular incidents are being investigated, and we may or may not really ever know what happened. We will do our darndest to find out what happened, because you just can’t tolerate a loss of a single life through your inability to work together.”

The Air War

The allied air war passed the 40,000-sortie mark Sunday, U.S. commanders said--some 10,000 more missions than were flown against Japan in the final 14 months of World War II.

Marines listening to the sound of B-52s dropping their bombs Saturday night described it as a long series of rumblings that went on for 90 minutes without a break.

“We’re blowing the hell out of them tonight,” said one Marine. “Wave after wave.”

Gen. Johnston said that at least 68 additional Iraqi warplanes had been destroyed when the hardened bunkers in which they were hidden were pounded by allied bombs.

He estimated that at least 99 Iraqi planes have been destroyed on the ground since the fighting began, and he said that number could approach 200 if the planes flown to Iran for apparent safekeeping are included.

Johnston said that 25 of the 35 bridges connecting Iraq with the Kuwaiti theater had been destroyed, causing huge backups of Iraqi convoys that were being systematically attacked.

The Marine general said that ground fire had been diminished to a few small-arms skirmishes and that the number of prisoners of war taken since the fighting began now stood at about 800. He also said, regarding the start of a ground offensive, that “there is no timetable we feel obliged to follow.”

Meanwhile, U.S. bombers struck back and possibly damaged or destroyed one Scud missile launching site, minutes after three Iraqi missiles were fired at targets in Saudi Arabia and Israel early Sunday, U.S. officials said.

The bombers attacked two Scud launch sites, and “pilots reported secondary explosions at one,” the U.S. military command said in a brief communique.

Secondary blasts usually indicate that a munitions vehicle or storage area has been hit, officers say.

“We did real good,” one military source said when asked the results of the attacks on the launch sites.

Israeli officials said two of the missiles landed in an area that includes parts of Israel and the occupied West Bank; no injuries were reported. The third missile was intercepted by a pair of U.S. Patriot air defense missiles as it approached Riyadh.

Sunday was a day in which the Iraqis once again dug in and held their defensive positions after a week during which they launched a three-pronged exploratory attack across the Saudi border that was harshly repulsed by both allied land and air bombardments.

“There is even less activity than yesterday,” said Group Capt. Niall Irving of Britain’s Royal Air Force. “There’s no theme in any direction. Perhaps they are considering the options left to them.

“I have no idea what the next phase might be. As far as we can tell, all of (Hussein’s) other assets have been taken out. He’s in a hopeless situation from a military standpoint.”

Irving said the British fliers concentrated on taking out petroleum storage and refining capabilities Sunday, as well as knocking out artillery on the island of Faylaka, just off the Kuwaiti coast, with 1,000-pound air-burst bombs.

Iraqi Threats

The interests of the United States “everywhere in the world will also be the target,” Baghdad Radio said in a report monitored in Nicosia, Cyprus. “There is a difference between terrorism and struggle. This is a legitimate act.

“The target will not be confined this time to the soldiers of the United States, the mercenaries of its allies or its collaborators in the holy lands in the Arabian Peninsula.”

Iraqi President Hussein last month urged Muslims everywhere to launch a holy war against the United States and its allies, who are fighting to end Iraq’s occupation of Kuwait.

Commenting on the most recent missiles aimed at Saudi Arabia and Israel, Baghdad Radio characterized Riyadh, the Saudi capital, as “the den of treason, disgrace, infidelity and atheism,” and said the Iraqi missile crews had dealt “a destructive blow” to Tel Aviv.

“O heroic men of the missile force, continue your blows; God is on your side,” the broadcast went on. continued. “The challenge will continue until they (the allies) recognize . . . our right to our land and the rights of our people of Palestine.”

The Nuclear Option

Cheney said Sunday that nuclear weapons would not be needed to defeat Iraqi forces. The use of the atomic bomb against Japan may have saved a million lives by eliminating the need for a ground invasion of the Japanese islands, Cheney said on ABC’s “This Week With David Brinkley.”

“That’s clearly not the situation we’re faced with here,” he said. “This is a different set of circumstances” that can be resolved using conventional weaponry, he said.

“We think the way to save substantial numbers of Americans is to do exactly what we’re doing, which is to use the conventional air power against his ground forces . . . and that appears to be working very well, and I would not, at this point, advocate the use of nuclear weapons, certainly,” the secretary said.

However, Iraq’s ambassador to France, Abdul Razzack Hamshimi, made it clear that Iraq was prepared to use chemical weapons. Interviewed on CNN, he said, “When a country’s being threatened, that country has the right to use whatever in its capabilities, whatever that country has to defend itself.”

Ramsey Clark

In a report cleared by Iraqi officials, the Associated Press said Clark arrived in Baghdad from Amman, Jordan, with a three-member delegation. He described his trip as a “peaceful mission.”

Clark, 63, visited Baghdad on a similar mission last year as tension mounted during the weeks before Jan. 17 when allied warplanes began their bombing raids into Iraq and Kuwait.

In 1989, Clark went to El Salvador and won the release of an American religious worker who had been accused of stockpiling weapons for rebel troops. He flew to Libya in 1986, three months after American jets attacked, and called the bombing a violation of international law. During the Iran hostage crisis in 1980, Clark traveled to Tehran, where he demanded freedom for the hostages and criticized American support for the deposed Shah of Iran.

Times staff writers John M. Broder in Washington and Mark Fineman in Amman, Jordan, contributed to this report.

THE CRASH OF THE B-52

A B-52 returning from a mission in Iraq went down in the Indian Ocean late Saturday. Military officials released the following information Sunday: * RESCUE: Three of the crew were rescued, and a search was continuing into Monday morning for the remaining three crew members.

* BASE: The bomber was en route to its base on Diego Garcia, a small island 2,000 miles south of the Persian Gulf.

* MALFUNCTION: It was the U.S. military’s “best estimate” that the huge bomber went down as a result of mechanical problems, not hostile fire.

* MISSION: The B-52 was returning from a mission “in support of Desert Storm,” according to a military briefing Sunday night in Riyadh, Saudi Arabia. There was no further information on the nature of the mission.