U.S. and Iraqi forces traded fire across the desert frontier Monday, and Iran's president made a surprise offer to hold direct talks with both Iraq and the United States to try to end the Persian Gulf war.

U.S. officials disclosed Monday that the battleship USS Missouri had used its 16-inch guns in action for the first time since the Korean War, targeting prefabricated concrete bunkers that the Iraqis were moving into place in Kuwait.The new diplomatic effort by Iranian President Hashemi Rafsanjani was reported by Iran's official Islamic Republic News Agency. It said he told a news conference in Tehran he is willing to talk with Iraqi President Saddam Hussein - and with Washington, provided Iran's spiritual leader Ayatollah Ali Khamenei approves.

White House spokesman Marlin Fitzwater and Defense Secretary Dick Cheney saw little merit in the offer. But the initiative was praised by Soviet officials and by U.N. Secretary-General Javier Perez de Cuellar, who said he hoped it would succeed.

The Iranians have been hostile to the United States since the 1979 Islamic revolution. They also fought a 1980-1988 war with Iraq and have condemned its seizure of Kuwait six months ago.

Rafsanjani said the Swiss have been acting as intermediaries with Washington on other issues and said "the same channel can be used" to start peace talks.

Iran says it is neutral in the war. But the allies were puzzled when Iraqi aircraft began seeking refuge in Iran - 89 by allied count. Iran has said the planes will be impounded until the war's end; the United States has said it will take the Tehran government at its word. U.S. commanders have said the Iraqi planes will be shot down if they try to leave Iran.

Meanwhile, the relentless attack by U.S. and allied warplanes has forced Iraqi soldiers to move in smaller convoys and top officers to seek protection in schools, U.S. military officials said Monday.

In the last 24 hours, officials said, the U.S. Air Force knocked out 25 Iraqi tanks moving in enemy territory and lost one UH-1 helicopter that crashed in a non-combat situation in Saudi Arabia, killing all four crewmen.

Allied warplanes also destroyed five to 10 vehicles moving through Kuwait, suggesting the air campaign has forced Iraqi ground forces to move in smaller convoys to avoid detection, Marine Maj. Gen. Robert Johnston said Monday.

At a separate news conference in Riyadh, the commander of Operation Desert Storm, Gen. H. Norman Schwarzkopf, said that allied air strikes have been so effective that senior Iraqi officers are moving their headquarters into schools because "they know we're not going to attack civilian targets."

The general said he hopes Iraq's claim of 321 civilian casualties from allied bombing was correct.

"I would say that if the number's only 321 I'm quite encouraged by that, because if they follow the same policies with regard to that as they've followed on everything else, you can divide by 10," Schwarzkopf said.

Allied warplanes pounded Baghdad before dawn Monday, and French warplanes hit positions of the Republican Guard in southern Iraq and Kuwait.

Witnesses in Baghdad said communication centers, government offices and industrial installations were hit - some of them for the second and third times since the war began nearly three weeks ago.

There is still no electricity in Baghdad and only intermittent water supplies. The city has been divided into five sectors, which receive water on a rotating basis.

In the Saudi port city of Jiddah, 9mm pistol or rifle shots were fired at a shuttle bus Sunday night, slightly injuring two U.S. military personnel with flying glass, officials said. No one was apprehended.

The military described it as the first such attack on American military personnel in Saudi Arabia.