WASHINGTON -- President Bush, increasingly concerned about a possible avian flu pandemic, revealed yesterday that any part of the country where the virus breaks out could likely be quarantined and that he is considering using the military to enforce it.

"The best way to deal with a pandemic is to isolate it and keep it isolated in the region in which it begins," he said during a wide-ranging Rose Garden news conference.

The president was asked if his recent talk of giving the military the lead in responding to large natural disasters such as Hurricane Katrina and other catastrophes was in part the result of his concerns that state and local personnel aren't up to the task of a flu outbreak.

"Yes," he replied.

After the bungled initial federal response to Katrina, Mr. Bush suggested putting the Pentagon in charge of search-and-rescue efforts in times of a major terrorist attack or similarly catastrophic natural disaster. He has argued that the armed forces have the ability to quickly mobilize the equipment, manpower and communications capabilities needed in times of crisis.

But such a shift could require a change in law, and some in Congress and the states worry that it would increase the power of the federal government at the expense of local control.

Mr. Bush made clear that the potential for an outbreak of avian flu is much on his mind, and has had him talking with "as many [world] leaders as I could find," consulting a book he read about the 1918 Spanish flu pandemic that killed 40 million and meeting with staff and experts. "I have thought through the scenarios of what an avian flu outbreak could mean," he said.

He acknowledged that a quarantine -- an idea sure to alarm many in the public -- is no small thing for the government to undertake and that enforcing it would be tricky. "It's one thing to shut down airplanes," Mr. Bush said. "It's another thing to prevent people from coming in to get exposed to the avian flu."

He urged Congress to give him the ability to use the military, if needed. "I think the president ought to have all ... assets on the table to be able to deal with something this significant," he said.

As a standby precaution, Mr. Bush in April signed an executive order that added pandemic influenza to the government's list of communicable diseases for which a quarantine is authorized. It gives the government legal authority to detain or isolate a passenger arriving in the United States to prevent an infection from spreading.

At the time the order was signed, a spokeswoman for the federal Centers for Disease Control and Prevention said the Public Health Service would probably recommend home quarantines when possible, but said they would be voluntary. It's unclear whether the federal takeover of state and local quarantine powers that Mr. Bush discussed yesterday would be limited just to travel or involve broader home quarantines as well.

Experts agree that there will certainly be another flu pandemic -- a new human flu strain that goes global. But it is unknown when or how severe that global epidemic will be -- or whether the H5N1 bird flu strain now circulating in Asian poultry will be its origin.

Just in case, experts are tracking the avian flu, which has swept through poultry populations in large swaths of Asia since 2003 and has now jumped to humans and killed at least 65 people.