But aviation insiders say that even with the additional measures, only a small percentage of the air freight originating overseas is likely to be examined before it arrives at U.S airports.
The Department of Homeland Security said it had “taken a number of steps to enhance security” in the wake of the incidents late Thursday and early Friday, in which two packages described as copy machine toner cartridges containing white powder and wires were intercepted after being shipped from Yemen for destinations in the U.S.
President Barack Obama later said the packages “apparently did contain explosive material” and constituted a “credible terrorist threat” against the U.S.
Homeland Security announced plans to implement additional security measures several hours before Obama’s comments.
“The public may recognize specific enhancements including heightened cargo screening and additional security at airport,” it said. “Passengers should continue to expect an unpredictable mix of security layers that include explosives trace detection, advanced imaging technology, canine teams and pat downs, among others. As always, we remind the public to remain vigilant and report suspicious activity to local law enforcement."
The additional cargo screening will extend anti-terrorism measures in an area that some experts say remains a weak link in the security chain.
The federal government already has more scrutiny for air cargo that travels on passenger planes.
Congress in 2007 passed legislation mandating that the Transportation Security Administration require air freight carriers to screen or physically inspect cargo loaded in the bellies of passenger planes at U.S. airports or bound for U.S. destinations. The law stipulated that 100 percent compliance be achieved by August 2010 under the oversight of the TSA, which monitors the program but performs no screening itself.
But freight traveling on cargo-only planes is not subjected to the same level of scrutiny. That’s because cargo jets have been considered unlikely terrorist targets, since attacks would claim only a few lives.
“Nobody would care,” said one former air cargo pilot, who spoke with msnbc.com on condition of anonymity.
As a result, said the former pilot and another expert familiar with air cargo procedures, also speaking on condition of anonymity, cargo picked up overseas for delivery to the U.S. depends largely on a system of mutual trust.
“They cannot check everything,” the ex-captain said, referring to U.S. cargo fliers such as DHL, FedEx and UPS. “They develop relationships with different suppliers, and they expect whoever is bringing it to the freight carrier to have checked and be sure where it came from. … Pretty much everyone trusts that the person before them has done the vetting.”
But as demonstrated by Friday's incidents, in which the two intercepted packages containing explosives reportedly were addressed to a synagogue and a Jewish community center in Chicago, such a system could enable terrorists to indirectly mount attacks far from home.
The TSA is attempting to reduce the risk from inbound international cargo by, among other things, creating a certification program for screeners.
But Rep. Edward J. Markey, D-Mass., who after the 9/11 attacks led the drive for laws requiring the screening of aircraft belly cargo and has introduced legislation requiring TSA to establish its own cargo screening facilities, said additional legislation also may be required.
“I will explore the need for legislation to mandate screening for air carriers that transport only cargo” in light of the air scare, he said in a statement issued Friday.
Any additional security measures would likely run into strong resistance from air cargo companies, including overseas carriers.
Some foreign-based carriers already are chafing under the U.S.-required security programs, saying that they increase overhead and cause delays.
British Airways Chairman Martin Broughton said at a conference Tuesday in Britain that the U.K. government should not “kowtow to the Americans every time they wanted something done” regarding aviation security.
According to the Financial Times, Broughton particularly criticized the requirement that passengers take off their shoes and remove laptops from their luggage during security checks and said the practice should be abandoned.
But whatever the resistance, changes in the way air cargo is handled are almost certain, said the former cargo pilot.
“It’s been almost like an old boys network,” he said of the current system of handling international shipments. “Clearly that’s not going to work anymore.”