All US commercial aircraft are to be thoroughly searched within the next day after box cutters, bleach and other suspicious items were discovered aboard two Southwest Airlines planes, US law enforcement and aviation officials said last night.
The FBI, working with the Department of Homeland Security, is investigating how items, which also included clay and matches, got on the planes. They were discovered by airline employees late on Thursday in plastic bags on two Boeing 737 aircraft on the ground in Houston and New Orleans.
The inspections of nearly 6,000 planes over the next 24 hours are not expected to create flight delays, the Federal Aviation Administration said.
Box cutters were used as a weapon by the September 11th, 2001, hijackers and have since been banned as carry-on items. Liquid bleach is not permitted on commercial flights, but some matches and clay are allowed, according to the homeland security agency's Transportation Security Administration.
FBI Director Robert Mueller, speaking to reporters in Houston, said the security breach was under investigation, but likely was not a serious threat.
"I will tell you that it does not appear to be a terrorist event and there is no imminent threat," he said. "There were no explosives, there was no imminent threat in terms of a capability to commit a terrorist act."
In Dallas, Southwest said in a statement that notes accompanying both packages indicated the items were intended to challenge the TSA checkpoint security procedures.
The suspicious items in New Orleans were found in a bathroom compartment. The airline said a similar discovery was made on the plane in Houston. Both were found during maintenance.
Southwest said it completed inspections of its entire fleet of 385 aircraft and found no additional items.
"We continue to cooperate with the TSA and FBI to determine the origin of these items," it said in a statement. "We will not speculate on who might have left these items onboard."
The inspection order is believed to be the first of its kind since the security administration was created after the attacks and took over airport security from the airlines.
Commercial aircraft are cleaned and checked for security before each flight by airline employees, but Friday's directive required a more thorough inspection of every plane, the officials said.
Houston-based Continental Airlines said in a statement it was "anticipating receiving instructions to inspect aircraft and we are planning to begin this immediately." It said no flight delays or cancellations were expected.
Law enforcement officials said the investigation is being led by the joint terrorism task forces in Houston and New Orleans.