The introduction to this GAO report states, "GAO investigators succeeded in passing through TSA security screening checkpoints undetected with components for several improvised explosive devices (IED) and an improvised incendiary device (IID) concealed in their carry-on luggage and on their persons. The components for these devices and the items used to conceal the components were commercially available.
Specific details regarding the device components and the methods of concealment GAO used during its covert testing are classified by TSA; as such, they are not discussed in this testimony.
Using publicly available information, GAO investigators identified two types of devices that a terrorist could use to cause severe damage to an airplane and threaten the safety of passengers. The first device was an IED made up of two parts -- a liquid explosive and a low-yield detonator. Although the detonator itself could function as an IED, investigators determined that it could also be used to set off a liquid explosive and cause even more damage. In addition, the second device was an IID created by combining commonly available products (one of which is a liquid) that TSA prohibits in carry-on luggage. Investigators obtained the components for these devices at local stores and over the Internet for less than $150. Tests that GAO performed at a national laboratory in July 2007, in addition to prior tests in February 2006 that GAO performed in partnership with a law enforcement organization in the Washington, D.C., metro area, clearly demonstrated that a terrorist using these devices could cause severe damage to an airplane and threaten the safety of passengers.
Investigators then devised methods to conceal the components for these
devices from TSA transportation security officers, keeping in mind TSA
policies related to liquids and other items, including prohibited items. By
using concealment methods for the components, two GAO investigators
demonstrated that it is possible to bring the components for several IEDs and one IID through TSA checkpoints and onto airline flights without being challenged by transportation security officers. In most cases, transportation security officers appeared to follow TSA procedures and used technology appropriately; however, GAO uncovered weaknesses in TSA screening procedures and other vulnerabilities as a result of these tests. For example, although transportation security officers generally enforced TSA's policies, investigators were able to bring a liquid component of the IID undetected through checkpoints by taking advantage of weaknesses identified in these policies. These weaknesses were identified based on a review of public information. TSA determined that specific details regarding these weaknesses are sensitive security information and are therefore not discussed in this testimony. GAO did not notice any difference between the performance of private screeners and transportation security officers during our tests."