Rep. Mike Rogers, R-Ala., commended him for the move. "I think it's common sense what you've done," Rogers said.
Not every congressman on the House Homeland Security subcommittee agreed. Rep. Bennie Thompson, D-Miss., held up a golf club and a hockey stick, asking whether they were dangerous.
"I think it could cause serious harm," Thompson said of the hockey stick.
Many flight attendants, pilots and even air marshals, who fly on commercial planes undercover, have come out against letting the items on board.
George Taylor, president for the federal air marshal service within the Federal Law Enforcement Office Association, said terrorists could figure out how to defeat reinforced cockpit doors with weapons similar to the box-cutters used on Sept. 11, 2001.
"It's just absolutely insane," said Taylor, a 36-year law enforcement officer who has been an air marshal since 9/11. "I don't put my faith in that reinforced door. If it's made by man, it can be broken by man."
"They're very upset," Taylor added, about fellow air marshals. "This is not the time to implement this policy."
Taylor spoke at a news conference outside the Capitol where flight attendants also sharply criticized the policy change. There, Rep. Ed Markey, D-Mass., threatened a House vote on his legislation to prohibit knives on planes if the TSA doesn't reverse course.
"The TSA policy makes no sense," said Markey, who held up a knife that is allowed with a longer blade than a box-cutter. "It is a dangerous policy."
At the hearing, Pistole showed lawmakers a video of the destructive force of the explosive found on a passenger in December 2009 that destroyed a sheet of plywood between two sawhorses.
"This is what I believe the TSA should be focused on," Pistole said. "It really comes down to how can we best utilize our resources."
He also showed lawmakers a display of small knives with other items that have been allowed since 2005, including scissors with blades less than 4 inches long, knitting needles and screwdrivers less than 7 inches long. He said TSA is still more restrictive than knives allowed in federal buildings.
"Given the overall intelligence, these are not things that terrorists are continuing to use," Pistole said of small knives.
Pistole acknowledged he could have consulted with flight attendants and pilots better before announcing the change in policy. But he said he was confident in his decision. "I think the decision is solid," he said.
Like in Congress, reaction elsewhere has been mixed to the change. Some security experts and frequent fliers praise reducing prohibited items that distract checkpoint officers from more dangerous ones. But some security analysts have said travelers have grown accustomed to leaving knives out of their carry-on bags, and the policy change isn't necessary.
The Coalition of Flight Attendant Unions, which represents 90,000 workers, has been strongly opposed and set up a White House petition with a link from noknivesonplanes.com.
"Any way you slice it, a knife like this is a weapon, and it doesn't belong on an airplane," said Laura Glading, president of the Association of Professional Flight Attendants, representing 16,000 workers at American Airlines. "His ridiculous position remains unchanged."