After attacking nearly 100 targets with 415 cruise missiles and hundreds of bombs, U.S. forces left tons of rubble last week where Iraq's Republican Guard soldiers once slept, where other security and intelligence units once worked and where President Saddam Hussein once pursued schemes to expand his missile arsenal.

But even as President Clinton was declaring the airstrikes a success and ending the operation late yesterday, the Pentagon was acknowledging that it had only a sketchy view of the impact that four nights of bombing had on the functioning of Saddam Hussein's military and security networks.

In preliminary estimates released earlier in the day, Pentagon analysts reported only 28 of the 97 targets hit in the first three nights were destroyed or severely damaged. Another 46 were characterized as lightly or moderately damaged and the remaining 23 had yet to be assessed.

Seeking to reconcile the victory claims with the damage assessments, Defense Secretary William S. Cohen and Gen. Henry H. Shelton, chairman of the Joint Chiefs of Staff, held what amounted to a seminar yesterday on how the Pentagon estimates destruction, insisting that even damage rated "light" or "moderate" in official reports can mean that the target was put out of business.

"It does appear that we've got to do a better job of translating the arcane science of battle damage assessment into plain English so that you can all relay the information more effectively to the public," the general told reporters at the news conference. "So the burden is on us."

The Pentagon leaders asserted that the bombing has set back Iraq's plans to develop longer-range missiles by at least a year. But they offered little else to measure the extent to which the airstrikes diminished Iraq's weapons-making capabilities and the threat that Baghdad poses to the region -- the goals they had set for Operation Desert Fox.

Cohen and Shelton, appearing jointly, said a detailed understanding of how much the military operation stymied Iraq's plans to make nuclear, biological and chemical weapons would take weeks, if not months. At the same time, they acknowledged that Iraq is likely to begin quickly to rebuild the damaged facilities.

"From the beginning of this operation, we've been careful to set realistic goals," Cohen said. "We've also been careful not to either overstate or exaggerate the results as intelligence analysts study the very preliminary data."

Shelton declared himself "very pleased with the results of the operation thus far," but conceded that the way in which the Pentagon reports its bombing results can give a less positive picture.

The damage assessment released yesterday showed somewhat greater destruction than a report Friday after the second night. Officials attributed this to a closer analysis of the targets and to the fact that some targets struck earlier in the week were hit again during the third night.

To demonstrate how the Pentagon's preliminary damage assessments often fail to convey the full impact of an attack, Cohen cited the terrorist bombing of the Oklahoma City federal building. He said that while the attack rendered the building functionally useless, U.S. government analysts looking at aerial photos initially rated the destruction as moderate.

"Some have characterized moderate damage as somehow being less than successful," Cohen said. But "when we make these preliminary assessments, what looks either to be light or moderate cannot be calibrated in terms of a normal understanding."

Shelton made the same point, citing the examples of the truck bombings earlier this year at the U.S. embassies in Kenya and Tanzania. He said U.S. analysts had categorized the damage there as light to moderate.

Producing an aerial picture of the Taji missile repair complex, Shelton pointed to several buildings hit by U.S. forces last week, causing varying degrees of damage from moderate to severe.

"My point is, none of these buildings within this compound were assessed as destroyed; not even one," the general said. "Our analysts are appropriately very conservative in their initial assessments. . . . But in my view, this facility will not be usable for Saddam's efforts to maintain or improve his missile capabilities in the years ahead.

"I'd also like to point out, as you can see, many of the buildings in this facility appear to be undamaged," he went on. "And the reason for that is because they were not targeted. We only went after specific buildings within the compound -- again, ones that were related to our mission objectives."

The attacks on missile production and research facilities, where U.S. officials said Iraq was working on long-range systems that could deliver weapons of mass destruction, were particularly important to the U.S. war plan. And they were all the more important since administration officials, to avoid civilian casualties, ruled out airstrikes against other commercial and industrial facilities with potential to manufacture chemical and biological weapons that these missiles could carry.

In addition to crippling the missile effort, Cohen and Shelton said the airstrikes caused significant damage to Saddam Hussein's security service and his communications, intelligence-gathering and propaganda networks.

"Saddam may rebuild and attempt to rebuild some of this military infrastructure in the future, just as he has replaced many facilities, including lavish palaces after" the 1991 Persian Gulf War, Cohen said. "But we have diminished his ability to threaten his neighbors with both conventional and nonconventional weapons."