RIYADH, SAUDI ARABIA, FEB. 13 -- After reciting the day's routine war reports, Brig. Gen. Richard Neal stepped away from the lectern, braced and declared in his Marine officer's voice: "I'm here to tell you it was a military bunker."

As his words hung there, a roomful of journalists was momentarily silent. For the first time in Operation Desert Storm, the U.S. military was dealing with the killing of of a large number of Iraqi civilians by U.S. bombs, and the response was as direct and uncompromising as the bombing campaign itself.

The public presentation appeared to have been carefully worked out. Neal's appearance was delayed while the U.S. military obtained its best information and arrayed its facts in the best light. To back up its contention, Gen. H. Norman Schwarzkopf's Desert Storm command provided the kind of detailed targeting and intelligence information it has refused repeatedly to disclose to reporters since the war began Jan. 17.

The same tone continued at a Pentagon briefing five hours later, as Lt. Gen. Thomas Kelly disclosed more intelligence information in making the military's case that the Baghdad building was a communications bunker.

"I think the simple fact is that we knew it was a command and control facility," said Kelly. "We targeted it, we bombed it very accurately. We bombed a building that had barbed wire around it, not an indication of a bomb shelter. We bombed a building that had a camouflage roof painted on it for whatever reason -- again, didn't look like a bomb shelter."

The later briefing produced more questions from reporters. One asked why, given the previous history of the Baghdad structure as an air-raid shelter, precautions had not been taken to make sure it was not being used for that purpose now. If U.S. intelligence could see Iraqi military personnel entering the shelter, why couldn't they see the civilians entering?

Kelly offered answers for the reporters' questions: The civilians may have entered at night, when it was hard to see them. The attack itself had taken place at 4:30 a.m. Baghdad time. As for the possible shelter use, "We did take all the precautions we could. Obviously we didn't know that the civilians were in there; we would not have bombed the thing."

But when all was said and done, the explanation that hung in the air was that U.S. bombing raids -- even on targets qualified as military by U.S. intelligence officers trying carefully to spare noncombatants -- also can kill civilians, no matter how accurate the ordnance or careful the pilots.

This was an accepted fact in Vietnam, where in a guerrilla-style war targeters took less care than now to avoid civilian casualties. It was even so in Grenada, where U.S. Navy bombers supporting an invasion that met practically no resistance destroyed a mental hospital and killed 21 patients.

In the 28 days and 67,000 sorties of massive Desert Storm bombing, however, Schwarzkopf's staff has deflected attention away from the casualties in Iraq and Kuwait. Although Neal and other officers have acknowledged that "collateral damage" would occur, there have been no body counts, civilian or military, and the only things U.S. briefers talk about "killing" are tanks and trucks.

But with the television images from Baghdad today, civilian casualties also became a fact in the Persian Gulf War. Their entry into the portrayal of Operation Desert Storm seemed all the more sudden and dramatic because Schwarzkopf's command had refused to discuss them before.

The reason civilians died in the shelter, Neal asserted, was that they were inside a hardened bunker that had been used routinely over the last several weeks by Iraqi officers communicating with their troops in the Kuwait theater. U.S. intelligence was able to hand that information to allied targeters because monitors had intercepted radio signals from the camouflaged shelter, he said, and U.S. satellites had photographed military vehicles parked outside and uniformed personnel coming and going.

Neal said the bunker had been on the U.S. command's "active target list" for some time, as the command and control activities were monitored. A senior U.S. officer added that U.S. targeters knew the installation was in a residential area, but were confident that their highly accurate smart bombs could destroy it without damaging civilian homes nearby.

In fact, that is what happened, with the laser-guided U.S. ordnance going down a ventilation shaft with perfect precision, he said. "You don't just do that by accident," Neal declared. "That requires planning."

An Iraqi national reporting from Baghdad for the Associated Press quoted survivors as saying 400 civilians died inside the shelter when two bombs exploded. He counted 40 bodies lying outside the installation, which he said was designated by arrows carrying the word shelter written in Arabic and English.

"If in fact that did occur, then it is a tragedy," Neal said. If the allied command had known the civilians were there, it would not have included the installation on the target list for today's early-morning Baghdad raids, he asserted.

Despite its detailed information, U.S. intelligence had nothing to indicate the shelter would contain civilians, Neal said. Iraqi authorities in the past have carefully forbidden civilians from approaching command and control facilities where officers deal with sensitive information, he added. The satellites that photographed military vehicles and uniformed personnel never showed civilians spending the night, he said.

Although the installation was built in 1985 as a civilian air-raid shelter for the 1980-88 Iran-Iraq war, U.S. intelligence gathered from construction workers revealed that it was hardened later with concrete and, more recently, satellite photos showed it had been painted over with camouflage designs and protected with a berm-like dirt bank, Neal explained.

"From the military point of view, nothing went wrong," he went on. "The target was hit as designated. But from a personal point of view, I am outraged that civilians were put in harm's way, and I lay the blame for that on the Iraqi leadership."

Schwarzkopf also was "outraged" when news reports from Baghdad reached the Riyadh war room with details of civilians who, survivors said, perished inside the burning shelter, the senior officer said.