Administration to Seek Balance in Airport Screening

With the Thanksgiving travel crush imminent, the chief of the Transportation Security Administration, John S. Pistole, said in a statement that his agency would try to make screening methods “as minimally invasive as possible.” But he gave no indication that the agency would reverse its move to full-body scanners, now deployed in 70 of 450 airports in the United States, and physical pat-downs for passengers who object to the scans.

“This has always been viewed as an evolving program that will be adapted as conditions warrant, and we greatly appreciate the cooperation and understanding of the American people,” Mr. Pistole said.

Security officials said the new procedures were the only way to detect explosives hidden under clothing. “We cannot forget that less than one year ago a suicide bomber with explosives in his underwear tried to bring down a plane over Detroit,” Mr. Pistole said.

The debate over the proper balance of security and privacy was unfolding as Al Qaeda in the Arabian Peninsula, the terrorist group responsible for the Detroit airliner bomb last Christmas and for placing explosive devices aboard cargo planes last month, threatened similar plots to sow fear, disrupt travel and transport, and impose huge costs on the United States.

“This strategy of attacking the enemy with smaller but more frequent operations is what some may refer to as the strategy of a thousand cuts,” the Yemen-based group said in a new issue of its English-language magazine, Inspire, which resembles a glossy publication but is available for download on militant Web sites. “The aim is to bleed the enemy to death.”

The T.S.A., which screens about two million air passengers a day, began testing the full-body scanners in 2007, installed them more widely starting last year and accelerated their use after the failed plot last Christmas. If a screener spots something suspicious on a scan, which shows an outline of the unclothed body, or if a passenger prefers to skip the scan, the passenger must undergo a physical search that many passengers have found intrusive.

The furor began after Nov. 1, when the agency introduced the more aggressive pat-down procedure. Despite the storm of criticism from passengers, pilots and members of Congress, agency officials point to opinion polls showing that about 80 percent of the public supports the use of body scanners. About 1 percent of passengers have opted out of the scanner and undergone pat-downs so far this month, officials said.

Congressional leaders have promised to hold hearings on the issue.

Still, the administration has appeared to be caught off guard by the outrage of some passengers. Mr. Pistole agreed on Saturday to demands from pilots that they be exempted from the searches, after critics noted that a pilot who wants to destroy a plane hardly needs explosives to do so.

On Saturday in Lisbon, President Obama acknowledged public complaints but said he had been told by T.S.A. and counterterrorism advisers that “at this point” the measures “are the only ones right now that they consider to be effective against the kind of threat that we saw in the Christmas Day bombing.”

Secretary of State Hillary Rodham Clinton said on NBC’s “Meet the Press” on Sunday that she did not want to “second guess” security officials, but added that “everyone, including our security experts, are looking for ways to diminish the impact on the traveling public.”

On another Sunday talk show, CBS’s “Face the Nation,” Mrs. Clinton said she would not like to go through a security pat-down.

“Not if I could avoid it,” she said. “No. I mean, who would?”

On CNN’s “State of the Union” on Sunday, Mr. Pistole, a 26-year F.B.I. veteran who took over at the T.S.A. in June, described the scanners and pat-downs as the last line of defense against terrorists who evade no-fly lists and the “behavior detection officers” looking out for suspicious conduct at airports.

“If they do opt out, we just want to make sure, for example, on Christmas Day,” Mr. Pistole said, in a clear reference to the underwear bomber, that “they receive a thorough pat-down so they don’t pose a risk to that plane.”

In a sense, the strategy trumpeted by Al Qaeda in the Arabian Peninsula in the new issue of Inspire represents a victory for Western counterterrorism. The group acknowledged that Sept. 11-style attacks may be impossible to organize without being detected by the expanded intelligence dragnet.

“Really, it’s a good marketing spin on a pretty desperate strategy,” said James Carafano, a security specialist at the Heritage Foundation.

But the magazine showed that Qaeda planners have an increasing awareness that smaller-scale attacks, including those focused on air cargo, can cause enormous economic damage and public anxiety.

“It has a particular impact, coming as it does at a time when we’re arguing about how to prevent the kind of attack the same group tried at Christmas,” said Bruce Hoffman, an expert on terrorism at Georgetown University.

Both Mr. Carafano and Mr. Hoffman said they would advise the administration to revise the screening procedures. Mr. Carafano said limiting the body scans and pat-downs to secondary screening, for travelers who raise suspicions, would be more sensible than expanding the costly scanners to all travelers.

Mr. Hoffman said the administration should move away from adding more layers of security for every passenger in response to every new plot and consider an Israeli-style approach to identify passengers who pose a particular risk, based on advance intelligence, questioning travelers and watching their behavior.

“We’ve had nine years of just grafting security measures one on another,” Mr. Hoffman said. “Maybe it’s time to step back, take a hard look and look for a new approach.”