LANGLEY AIR FORCE BASE, Va. — In devising the targeting plan for a possible war against Iraq, U.S. military planners are hoping to reduce the potential for civilian casualties by using a new computer program whose name belies its serious purpose: "Bugsplat."

Approved two months ago, the program represents a significant departure from the traditional method of drawing a simple circle around a target to show a bomb's estimated blast effect and determine what civilians might be at risk nearby, Air Force officials said.

Instead, Bugsplat generates bloblike images — resembling squashed insects — that military officials say more precisely model potential damage by a particular type and size of bomb dropped by a particular aircraft flying at a given altitude. This enables commanders to fine-tune attacks and, in some instances, can embolden them to order bigger bombs than they would have employed relying on less-sophisticated modeling methods, the officials said.

"It's a significant advance," said Brig. Gen. Kelvin Coppock, director of intelligence for the Air Combat Command. "It will allow us to target those facilities that we want to target with confidence that we're not going to cause collateral damage."

The availability of more precise laser- and satellite-guided weapons and of more capable intelligence-gathering aircraft has given targeting specialists more options in deciding how to stage attacks with minimal collateral damage, officials said.

Even so, U.S. airstrikes continue to take significant civilian tolls, intensifying pressure on the Pentagon to exercise greater care. Investigations by journalists and human-rights advocates have documented that, as recently as the first four months of the war in Afghanistan, more than 800 civilians were killed in U.S. bombing. More than 500 civilians died as a result of 78 days of airstrikes over Serbia in 1999.

The Bugsplat program takes account of the dynamics of specific munitions as well as the characteristics of the terrain or objects being struck to predict an often irregular pattern of damage. But some defense experts familiar with the program are withholding judgment, noting that it has yet to be put to the test in war. They suggest it may have limited effectiveness against the most difficult targeting challenge confronting today's air commanders: mounting rapid strikes against suddenly discovered mobile targets such as missile launchers and ground vehicles.

"Because the program hasn't been used for actual targeting, this will be learn as you go," said Sarah Sewall, who is directing a study on civilian suffering in war at Harvard University.

The Pentagon's war plan for Iraq calls for dropping about 3,000 precision-guided bombs and missiles in the initial two days of the air campaign, according to officials. Attacks would be carried out by about 500 Air Force attack, radar-jamming and support planes and by Navy planes from five aircraft carriers, each carrying about 80 attack and support aircraft. The objective will be not just to destroy targets but also to sow chaos and confusion among Iraqi leaders and armed forces, the officials said.

Collateral-damage assessments come into play when an attack plan is being drawn up. Each potential target is examined for proximity to civilians or civilian property, which is where Bugsplat is intended to help. To lessen potential collateral damage, targeting specialists can try substituting a smaller weapon or one with a delayed fuse that lets a bomb penetrate first and then detonate. Changing the type of aircraft and its angle of attack also can make a difference, officials said.

If Bugsplat fails to resolve questions about a bomb's projected blast effect, a proposed attack can be sent for review to the Joint Warfighting Analysis Center in Dahlgren, Va., which developed Bugsplat and has even more sophisticated analysis tools. But this option takes time, at least four hours, officials said, compared with five to 10 minutes to run Bugsplat.

Although still commonly referred to as Bugsplat, the computer program was recently given a more formal name: FAST-CD, or Fast Assessment Strike Tool — Collateral Damage.

The fact that an attack may be projected to result in civilian deaths is not by itself cause to eliminate it under international law, said Brig. Gen. Charles Dunlap, the senior Air Force lawyer at Langley. The military advantage of striking a target can be deemed to outweigh the potential death toll.

Some military officials expressed reservations about relying too much on targeting models such as Bugsplat.

"They're great tools, but what I'm concerned about is, warfighting is an art, and there are certain things that only reside in the mind of a commander, so we can't abdicate to computers these kinds of decisions," Dunlap said.

Dunlap also noted that such computer tools will create a record of the options that commanders faced in drawing up a war plan, making them more accountable than ever for their actions.

"If they deviate from these decision support tools, they will need to be able to explain themselves later on," he said.