America’s transport watchdog vowed on Tuesday not to slow global trade by piling security measures onto the aviation industry in response to terror threats as air lobby group IATA warned against rash action.

“Security cannot bring business to a standstill,” said John Pistole, who was made head of the U.S. Transportation Security Administration (TSA) earlier this year, at an aviation security conference on Tuesday.

“We must strike that balance (between security and business). The U.S. government understands this well.”

Two packages containing bombs — both sent from Yemen and addressed to synagogues in Chicago — were intercepted in Britain and Dubai on Friday.

One of the packages was found on a United Parcel Service (UPS.N) cargo plane at East Midlands Airport in Britain. The other was discovered in a computer printer cartridge in a parcel at a FedEx  facility in Dubai.

Air cargo accounts for just over a third of global trade by value, and airline industry body International Air Transport Association (IATA) warned that knee-jerk regulatory reactions by governments could impede the flow of goods.

“We have seen many cases where (solutions) have unintended consequences,” said Giovanni Bisignani, Director General of IATA, at the conference.