The new policy conforms U.S. security standards to international standards, and allows TSA to concentrate its energies on more serious safety threats, the agency said in a statement.
The announcement, made by TSA Administrator John Pistole at an airline industry gathering in New York, drew an immediate outcry from unions representing flight attendants and other airline workers, who said the items are still dangerous in the hands of the wrong passengers.
Transport Workers Union Local 556, which represents more than 10,000 flight attendants at Southwest Airlines, called the new policy "dangerous" and "shortsighted," saying it was designed to make "the lives of TSA staff easier, but not make flights safer."
"While we agree that a passenger wielding a small knife or swinging a golf club or hockey stick poses less of a threat to the pilot locked in the cockpit, these are real threats to passengers and flight attendants in the passenger cabin," the union said in a statement.
The policy change was based on a recommendation from an internal TSA working group, which decided the items represented no real danger, David Castelveter, a spokesman for the agency, said.
The presence on flights of gun-carrying pilots traveling as passengers, federal air marshals and airline crew members trained in self-defense provide additional layers of security to protect against misuse of the items, he said.
There has been a gradual easing of some of the security measures applied to airline passengers after the Sept. 11, 2001, terrorist attacks. In 2005, the TSA changed its policies to allow passengers to carry on airplanes small scissors, knitting needles, tweezers, nail clippers and up to four books of matches. The move came as the agency turned its focus toward keeping explosives off planes, because intelligence officials believed that was the greatest threat to commercial aviation.
And in September 2011, the TSA no longer required children 12 years old and under to remove their shoes at airport checkpoints. The agency recently issued new guidelines for travelers 75 and older so they can avoid removing shoes and light jackets when they go through airport security checkpoints.