The US Transport Security Administration (TSA), has said it will allow passengers to carry some small pocket knives in their hand luggage for the first time since the 9/11 attacks.
As of 25 April, passengers may bring blades shorter than 2.36in (6cm) and narrower than 0.5in into plane cabins.
Ski poles, hockey sticks, and billiard cues will also be allowed on board in the move, which flight attendants warn will put passengers and crew at risk.
The TSA said the new rules would bring the US into line with international guidelines and offer a better experience for passengers.
David Castelveter, a spokesman for TSA, told the Daily Telegraph that the policy change was based on a recommendation from an internal TSA working group, which decided the items represented no real danger.
According to the BBC, he said: "This is part of an overall risk-based security approach, which allows Transportation Security officers to better focus their efforts on finding higher-threat items such as explosives."
While Mr Castelveter said armed pilots, federal air marshals and airline crew members trained in self-defence provide security to protect against misuse of the items, there was outcry from unions representing flight attendants.
Transport Workers Union Local 556, which represents more than 10,000 flight attendants at Southwest Airlines, called the new policy "dangerous" and "shortsighted".
According to the Daily Telegraph, a union statement said:"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."
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