Transportation Security Administration head John Pistole said in a statement that the agency would work to make screening methods "as minimally invasive as possible," although he gave no indication that screening changes were imminent.
The statement came just hours after Pistole, in a TV interview, said that while the full-body scans and pat-downs could be intrusive and uncomfortable, the high threat level required their use. "No, we're not changing the policies," he told CNN's "State of the Union."
Pistole said that, as in all nationwide security programs, "there is a continual process of refinement and adjustment to ensure that best practices are applied."
Still, he pointed to the alleged attempt by a Nigerian with explosives in his underwear to try to bring down an Amsterdam-to-Detroit flight last Christmas. "We all wish we lived in a world where security procedures at airports weren't necessary," Pistole said, "but that just isn't the case."
In his earlier TV appearance, Pistole appeared to shrug off statements by President Barack Obama and Secretary of State Hillary Rodham Clinton that the agency would look for ways to alter screening techniques that some passengers say are invasions of privacy.
Obama said in Lisbon on Saturday that he had asked TSA officials whether there's a less intrusive way to ensure travel safety. "I understand people's frustrations," he said, adding that he had told the TSA that "you have to constantly refine and measure whether what we're doing is the only way to assure the American people's safety."
Clinton, appearing Sunday on NBC's "Meet the Press," said she thought "everyone, including our security experts, are looking for ways to diminish the impact on the traveling public" and that "striking the right balance is what this is about."
She, for one, wouldn't like to submit to a security pat-down.
"Not if I could avoid it. No. I mean, who would?" Clinton told CBS' "Face the Nation" in an interview broadcast Sunday.
"Clearly it's invasive, it's not comfortable," Pistole said of the scans and pat-downs during the TV interview. But, he added, "if we are to detect terrorists, who have again proven innovative and creative in their design and implementation of bombs that are going to blow up airplanes and kill people, then we have to do something that prevents that."
Rep. John Mica, R-Fla. who is set to become Transportation Committee chairman when Republicans take over the House in January, differed with the approach.
"I don't think the rollout was good and the application is even worse. This does need to be refined. But he's saying it's the only tool and I believe that's wrong," Mica, a longtime critic of the TSA, said separately on the CNN program.
With the peak traveling season nearing, air travelers are protesting new requirements at some U.S. airports that they must pass through full-body scanners that produce a virtually naked image. The screener, who sits in a different location, does not see the face of the person being screened and does not know the traveler's identity.
Those who refuse to go through the scanners are subject to thorough pat-downs that include agency officials touching the clothed genital areas of passengers.
Pistole was shown videos of people being patted down where the screeners touched the breasts of a woman, felt into the pants of another person and felt the crotch of a man. He said all three cases were proper and that the gloves of the screener who felt inside the pants were then tested for explosive trace residue.
Pistole added that very few people receive the pat-down. People who go through the new advanced imaging machines available at some 70 airports are usually not subject to pat-downs, he said.
Pistole said that while watch lists and other intelligence sources help the TSA pick out travelers who might pose greater risks, rules against profiling mean that some people who are less of a risk, such as the elderly or the disabled, must sometimes undergo pat-downs.
"I want to be sympathetic to each of the negative experiences. We've had extensive outreach to a number of different disability community groups, a number of different outreach efforts to try to say, how can we best work with those in your community to effect security while respecting your dignity and privacy," he said.
House Majority Leader Steny Hoyer, D-Md., appearing on CBS, said Congress would hold hearings on the "very controversial" issue of how to strike the right balance. Asked how he would feel about submitting to a pat-down, Hoyer said: "I don't think any of us feel that the discomfort and the delay is something that we like, but most people understand that we've got to keep airplanes safe."