The Transportation Security Administration (TSA) said it was postponing a controversial change in rules which would have allowed passengers to carry small knives on planes.
The TSA last month said it was relaxing its rules on pocket knives -- banned on aircraft since the September 11, 2001 terror attacks -- in order to bring US rules into line with international regulations.
However the move prompted an outcry from pilots, flight attendants and airline executives.
In a statement released on Monday, one week after the twin bombings of the Boston Marathon, the TSA said it was delaying implementation of the rule change, which had been due to take effect on April 25.
The TSA said it was postponing the new security regime in order to "accommodate further input" from the Aviation Security Advisory Committee (ASAC), which includes members of the aviation community, passenger advocates and law enforcement experts.
"...TSA will temporarily delay implementation of changes to the Prohibited Items List, originally scheduled to go into effect April 25," the statement said.
"This timing will enable TSA to incorporate the ASAC's feedback about the changes to the Prohibited Items List and continue workforce training."
The Flight Attendants Union Coalition, which represents some 90,000 workers, had condemned the proposal to allow passengers to carry small knives with folding blades in their hand luggage.
"The continued ban on dangerous objects is an integral layer in aviation security and must remain in place," the group said last month.
The Coalition of Airline Pilots Associations had also spoken out strongly against the move.
"We believe the threat is still real and the removal of any layer of security will put crewmembers and the flying public unnecessarily in harm's way," CAPA president Mike Karn warned.