WASHINGTON (CN) - Transportation Security Administration head John Pistole defended the agency's use of the controversial pat-down procedure in airport security lines, saying the vast majority of passengers will not be subject to the procedure.
"The bottom line is few people in the overall scheme of things will actually receive those pat downs," Pistole said in a congressional hearing last week.
Fewer than 3 percent of travelers will undergo a pat-down, and only 1 percent of travelers opt out of going through the advanced imaging body scanner, the TSA states on its blog.
Pistole also emphasized that the policy is evolving.
"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," Pistole said in a statement Monday.
The administration has adopted that stance that the procedures will evolve.
"These are procedures that will continue to evolve," White House Press Secretary Robert Gibbs said Monday. "Just in the past year we've seen the Christmas Day attempt by [Umar Farouk] Abdulmutallab to blow up an airplane using a device that, as the president said, would not have and was not picked up by a simple metal detector."
Gibbs also noted the Yemen-based terror plot in October in which al-Qaida tried to set off explosives concealed in ink cartridges in airplane cargo headed to the United States.
"It would be nice to live in a world where that wasn't necessary," Gibbs said of the enhanced security measures. He said he passed through a full-body scanner in an airport recently.
On Monday, the TSA released a public service announcement justifying the new procedures.
"As you travel this holiday season, I want to remind you that TSA's mission is to ensure the safety of you, the traveling public," Pistole says in the videotaped message. "And we are committed to doing so efficiently, courteously and professionally."
Pistole and White House officials said the agency is working to make the screenings as "minimally invasive" as possible. Pat-downs are performed by TSA employees of the same gender as the passenger, and a passenger can request to have the pat-down in a private room with a witness of the passenger's choice.
TSA officers also explain the pat-down process before and during the procedure, Pistole said, and only a small number of passengers are subjected to the practice.
As passengers go through security, they are directed to pass through either an X-ray machine or an advanced body imaging scanner. Pat-downs are only given to passengers who set off the metal detector or opt-out of the full-body scanner.
Homeland Security Secretary Janet Napolitano has endorsed the procedure.
"There is a continued threat against aviation," Napolitano said in a press conference Monday. "We hope people will not opt out. We hope people will appreciate and understand the goal, the purpose and the need of what is being done."
Pistole said the TSA is trying "to strike the right balance between privacy and security."
"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," Pistole said Monday. "The terrorists allegedly behind the thwarted cargo attempt last month are out there bragging about how they will strike again."
Deputy Press Secretary Bill Burton said on Tuesday that President Obama supports the TSA measures.
"The president's view is we're going to continue to do what we can to use the best possible methods, the best possible intelligence to stop any harms coming to the American people," Burton said.