TSA chief John Pistole has stuck by his decision to allow passengers to bring knives on passenger planes for the first time since 9/11.
Stacy Martin, president of Southwest Airlines' flight-attendants union, called the decision "outrageous."
And by this week, more than 20,000 people had signed a petition to whitehouse.gov calling on the TSA to reverse the decision.
However, Pistole told a subcommittee of the House Homeland Security Committee on Thursday that he did not believe that small folding knives would enable a terrorist to take over a plane.
Also, finding some 2,000 small knives a day on passengers or in their carry-on bags and eliminating them was time-consuming, he said, the Associated Press reported.
He told lawmakers:
"It is the judgment of many security experts worldwide, which I agree with, that a small pocket knife is simply not going to result in the catastrophic failure of an aircraft, and an improvised explosive device will. And we know, from internal covert testing, searching for these items, which will not blow up an aircraft, can distract our officers from focusing on the components of an improvised explosive device."
In response, Rep. Eric Swalwell, D-California — who has said he is "mystified" by the TSA decision — pointed out that threats posed by bombs did not mean knives weren't dangerous.
"Just because this is a new threat does not mean that old threats don't still exist."
According to CNN, the TSA decision came after a threat assessment found that allowing small knives in cabins would not result in catastrophic damage to aircraft.
However, box cutters and razor blades were to remain on the prohibited items list.
AP cited several lawmakers at the hearing as saying they did not see much difference between the knives and the box cutters used by terrorists in the Sept. 11, 2001 attacks.
In the last three months of 2012, screeners at Los Angeles International Airport seized 47 of the small knives each day, according to Air Transportation World.
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