ABOARD THE USS ANTIETAM, AUG. 14 -- Until about four days ago, the most potent weapon on this U.S. fighting ship in the Persian Gulf -- Tomahawk cruise missiles capable of striking deep inside Iraq -- were not programmed to hit key Iraqi targets.

The reason: Ship computers that store data telling the Tomahawks how to reach potential military targets in the gulf region didn't have much guidance information about important Kuwaiti and Iraqi facilities, according to an officer on board. Computer programmers had not anticipated an Iraqi invasion of Kuwait, so the ship's electronic library of target data was thin.

Now that's changed, the officer said. After Iraqi tanks rolled into Kuwait Aug. 2, U.S. satellites hurriedly began taking pictures and dumping data into the Antietam's computer. Today, the ship's battery of Tomahawks is capable of striking a wide variety of Iraqi targets, the officer said.

The diplomatic waiting game that is developing in the Middle East is helping U.S.-led multinational forces in the region increase their preparedness for any possible armed conflict with Iraq. While Arab and Western leaders meet to talk about potential diplomatic solutions to the crisis, a massive military buildup continues as U.S. forces conduct daily exercises, hold planning sessions and ready their sophisticated weaponry for possible deployment against Iraq.

But a trip to the missile-laden Antietam and interviews with officers and seamen suggest that the waiting game in the gulf works both ways. The summer heat is searing, and desert dust blows continually, even at sea, putting stress on machinery and forcing commanders to alter routines to keep sailors and airmen alert. If the tense wait continues for long, officers and seamen said, morale is likely to wither.

"The heat and humidity is hard on everybody," said the Antietam's executive officer, who can't be identified according to media ground rules set by the Navy. "Most Navy systems are not designed to operate in these conditions. We have to work extra hard to clean things. . . . It's a different operating environment."

A seaman in the ship's mess added: "It already seems like we've been here forever. . . . It's real hot. You can imagine how it affects people."

Temperatures in the ship's engine room soar to 107 degrees. Sea water pumped into the ship from the gulf for cleaning and other purposes runs as high as 95 degrees.

"Alertness will become more of a problem as time goes on," said Lawrence Eddingfield, the Antietam's captain. "We have to make sure that people's senses remain keyed to the fact that we're still in a hostile environment."

At the moment, however, the military buildup appears to have instilled a keen awareness that war may be imminent. Inside the Antietam's glowing, multi-screened radar and Combat Information Center, technicians on high-alert status track dozens of ships and planes moving through the gulf, using sensors and computers to identify potential enemies.

These days, the screens mainly show scores of U.S. ships and aircraft recently deployed in and around the gulf. At present, there are about 24 ships, 17,000 men and 200 aircraft in the U.S. Navy's Joint Middle East Task Force, according to its commanding officer, Rear Adm. William Fogarty.

Naval forces in the region now include two aircraft-carrier battle groups, one at the mouth of the Persian Gulf and the other in the Red Sea, as well as eight fighting ships in the gulf itself. The Antietam, an Aegis cruiser carrying Tomahawk, Harpoon and SM-2 missiles, is the most heavily armed vessel in the gulf. The Navy-led task force is coordinating its operations with U.S. Army, Air Force and Marine units taking up positions in the nearby Saudi Arabian desert.

"The forces are in a deterrence, defensive disposition," Fogerty said today. "Of course, if deterrence fails, we will take appropriate action as directed."

On the Antietam, officers said they are trying to strike a balance between urging their mostly young crew members to be ready to fight and restraining them from developing itchy trigger fingers. Officers and seamen alike said they have been eager for information about the developing crisis.

Wire service reports are posted daily on ship bulletin boards. When President Bush delivered his speech a week ago announcing deployment of U.S. forces to Saudi Arabia, ship technicians recorded his remarks from the radio, and Eddingfield ordered that the speech be replayed for the Antietam's 404-man crew.

"They can read as well as I can about how many Americans are in Kuwait and Baghdad," Eddingfield said. "I'm not trying to hide anything from them. You want them to know that, hey, this is a difficult situation. I hope the powers that be can come to a diplomatic solution . . . {but} the president has said if Saudi Arabia is attacked, it's of vital interest of the United States."

Eddingfield said he thought morale on the ship had been bolstered by the rare international solidarity that has emerged since the Iraqi invasion, but he expressed weariness about as yet uncompleted efforts to form a multinational command system that would help coordinate the U.S., Arab, European and Asian forces now heading toward the gulf.

"All I can think of is Europe in World War II and all the difficulties {in military coordination} that brought to bear," Eddingfield said. "I'm sure they'll think about that before they're finished."

Type: Aegis guided-missile cruiser

Displacement: 9,600 tons, fully loaded

Length: 567 feet

Maximum speed: 30-plus knots

Complement: 364 (24 officers)

Weapons: Tomahawk long-range cruise missiles, Harpoon anti-ship and land-attack cruise missiles; Mark 46 torpedoes; Phalanx Close-in Weapons System, a six-barreled Gatling gun that can fire at a rate of 3,000 rounds a minute.

Background: Among the Navy's most heavily armed warships, the Antietam and others in the Ticonderoga class are capable of a variety of combat missions. They are frequently used to support aircraft carrier or battleship battle groups.

SOURCE: "Jane's Fighting Ships"; Navy Fact File