The nation's military brain trust, the Joint Chiefs of Staff, got its new heads Monday.

Air Force General Richard Myers was sworn in as the top officer of the Armed Services and Marine General Peter Pace officially assumed the post of vice chairman.

President Bush said he was pleased to have Myers and Pace taking their roles at this critical period when the United States is just beginning its war on terror.

"General Myers is known for his calm manner, sound judgment and his clear strategic thinking. Now, at any time, those qualities would be important, but today they're indispensable," Bush said at a welcome ceremony in Fort Myers, Va., outside Washington, D.C. "He and his outstanding vice chairman have assumed crucial positions at a crucial hour, and our country is thankful for your service."

Speaking at the ceremony, Myers said he was sure that America's soldiers were surprised to find themselves fighting a war on terror, but even as they did so, he was going to make sure their needs were met on and off the field.

"I couldn't be prouder to represent America's fighting men and women back here in Washington, D.C., and to serve as their advocate in helping ensure a quality of life for them that is commensurate with the obligations, the sacrifices and the risks that they shoulder on behalf of our great nation," Myers said.

The ceremony went on with its expected pomp even as the U.S. continued its 24-hour air assault on Afghanistan.

Pentagon officials last week said that they were running out of targets but they changed their tune Monday, saying new intelligence is providing additional sites for aircraft.

"The target set that existed at the outset has been enhanced by additional attention from the ground and by additional tension in the air," Myers said at a separate Pentagon briefing.

Over the weekend, carrier-based aircraft, long-range bombers and Tomahawk missiles hit 24 targets across Afghanistan — from airfields and air defenses to troop staging areas and terrorist training camps.

One target hit was in Korum, just west of Jalalabad. Senior military officials say laser-guided "bunker buster" bombs were used to take out ammunition storage areas in two tunnels.

Taliban leaders said more than 200 civilians were killed in the attack. Pentagon officials said if anyone was killed there, it was likely from their proximity to stored munitions that exploded on the ground after the attack. Defense Secretary Donald Rumsfeld said the secondary explosions indicate what kind of target was hit.

"They were not cooking cookies inside those tunnels. I mean, let's face it. You do not spend that kind of money and dig that far in and store that many weapons and munitions that it would cause that kind of sustained secondary explosions, unless you have very serious purposes for doing it," Rumsfeld said.

Rumsfeld called the Taliban leadership "accomplished liars," describing their journalist tours of civilian damage as propaganda and their estimates of the number of civilian casualties as "ridiculous."

Rumsfeld said that one errant missile killed four civilians, but any other reports of civilian casualties were inaccurate.

Asked why the United States had not directly helped Northern Alliance fighters by bombing Taliban troops on the front lines, Rumsfeld said that may be a future tactic.

"I suspect that in the period ahead — that's not going to be a very safe place to be," he said.

Meanwhile, in an effort to reach the hearts and minds of the people of Afghanistan, the United States has dropped thousands of leaflets. One shows a western soldier shaking hands with a man in traditional Afghan dress. The message in native languages Dari and Pashtu, say, "The partnership of nations is here to help."

"We're working to make clear to the Afghan people that we support them and we want to help free their nation from the grip of the Taliban and their foreign terrorist allies," Rumsfeld said, reiterating that the campaign is being fought on many fronts: military, humanitarian, information, diplomatic, financial, and economic.