The air campaign unleashed against Iraq yesterday was designed to deliver more bombs and missiles with greater precision than ever before, in the hope of not only disabling Iraqi forces but also compelling a quick surrender.

But for all their intensity, the first waves of strikes were carefully calibrated to focus on government and military facilities, avoiding damage to power plants, bridges and other structures that serve important civilian functions. Even as government buildings in central Baghdad exploded in flames, for instance, the electricity in the capital stayed on.

Plans for the bombardment, widely dubbed "shock and awe," called for more than 1,500 strikes in the first 24 hours. Nearly 1,000 were with air- and sea-launched cruise missiles and the rest with bombs dropped by Air Force B-1, B-2, B-52, F-15E and F-117 aircraft, and Navy F-14 and F-18 jets, flying off five aircraft carriers. British warplanes also participated.

Some targets are associated directly with Iraqi President Saddam Hussein, including palace complexes in Baghdad and in his home town of Tikrit. Many others are connected with the Iraqi military and security forces, including headquarters buildings, other command structures, communications links, air defense sites and suspected storage areas for chemical or biological weapons. Facilities were struck in the northern cities of Kirkuk and Mosul as well as in Baghdad and Tikrit.

Iraqi forces in the field are not being targeted yet, several officials said. Conventional military units also are largely being spared, with the emphasis on facilities belonging to troops considered most loyal to the regime -- Republican Guard divisions, Special Republican Guard units and the Special Security Office.

Televised images yesterday of the first wave of attacks demolishing buildings in central Baghdad prompted some comparisons with the indiscriminate bombing campaigns of World War II.

"There is no comparison," Defense Secretary Donald H. Rumsfeld declared at a Pentagon news conference, alluding to the TV commentary. "The weapons that are being used today have a degree of precision that no one ever dreamt of in a prior conflict."

But other defense officials acknowledged that the planned bombing, because of its scale and complexity, ran the risk of raising civilian deaths and damage to civilian property to levels that could undercut the U.S. war campaign.

Yesterday's escalation came nearly two days after the first U.S. air attacks of the war, which included an assault on a compound in southeastern Baghdad suspected of housing Hussein and his two sons. Gen. Richard B. Myers, chairman of the Joint Chiefs of Staff, disclosed yesterday that two other targets in Baghdad were struck in that pre-dawn raid -- the intelligence service headquarters and a Republican Guard facility.

Later that day, he added, sea-launched cruise missiles were sent against eight targets in Baghdad, including several Special Security Organization sites and three Republican Guard targets in Kirkuk.

Those limited attacks raised speculation that the Bush administration had changed its initial war plan and was delaying the start of a much more aggressive bombing campaign that had been widely forecast. But Pentagon officials said yesterday that the original timetable had provided for the large-scale air campaign to begin at about the hour it did -- 9 p.m. in Baghdad (1 p.m. EST).

That plan also called for U.S. and British ground troops to push off into Iraq from Kuwait about nine hours after the bombing started. That sequence was reversed, officials said, with U.S. military commanders deciding to initiate the ground campaign yesterday, one day ahead of the escalated bombing.

Pentagon officials cited two reasons for the adjustment. One was concern that the ground forces had become the target of sporadic but menacing Iraqi missile attacks. The second was alarm that some oil fields in southern Iraq were being set on fire.

With the advance of the ground troops and evidence that Iraq's leadership was in some disarray as a result of the first air attacks, U.S. officials had continued to hope for an early capitulation. Public appeals and secret contacts aimed at persuading Iraqi forces to surrender were stepped up.

But Rumsfeld indicated yesterday that the decision was made to proceed with the air campaign after concluding that other efforts at persuasion were not working.

"It was the absolute last choice, after every single other thing that could be done had been done," he said at a Pentagon news conference.

Other officials noted that the air campaign plan is flexible and can be adjusted in response to developments in Iraq.

The United States and Britain have amassed an air force of more than 1,200 warplanes in the gulf region, about 250 of them on five Navy aircraft carriers -- three in the Persian Gulf and two in the eastern Mediterranean. Blocked yesterday from using Turkish airspace to get over Iraq, the Navy planes taking off from the Mediterranean flew through Egyptian and Saudi Arabian skies, defense officials said.

U.S. officials said Iraq's small, weakened air force made no attempt to challenge the American and British warplanes.

With about 2,000 sorties planned for the first 24 hours, the escalated campaign involves fewer than the 2,800 sorties flown on the first day of the 1991 Persian Gulf War. But defense officials said the current campaign promises to be more efficient and effective than the one 12 years ago, when only about 10 percent of the munitions used were precision-guided. By contrast, every bomb and missile used yesterday was laser- or satellite-guided.

The satellite-guided munitions, called JDAMs, did not exist a decade ago. The B-1 bomber can now carry 24 JDAMs, for use against 24 separate targets. The advent of the B-2 bomber, which was added to the U.S. arsenal in 1993, also allows for multiple targets to be hit on a single pass.

In the run-up to the war, defense officials had suggested that the air campaign would showcase what in military jargon is being called "effects-based operations." Essentially, this involves trying to limit the number of munitions that are fired by focusing on the overall effect desired, rather than the extent of destruction.

Under the traditional targeting approach, for instance, if the idea was to shut off the electrical power of an enemy, every power station might be bombed. With the "effects-based" approach, only a few nodes might be hit to produce the same result.

"You do not have to attack each element of that system to make the system not work," Air Force Col. Gary Crowder, chief of strategy, concepts and doctrine at Air Combat Command, which supervises combat aircraft, said at a Pentagon briefing this week.