should be required to produce positive identification. Sellers should be required to keep records of sales transactions for a specified period of time.
At greatly increased levels of threat, the committee recommends the following additional controls:
Sellers of bulk detonable nitrate fertilizers should be required to have licenses, and purchasers should be required to obtain permits.
Packaged ammonium nitrate-based fertilizers typically sold in retail outlets should be sold only as nondetonable mixtures (as defined by a standard test protocol developed in response to Recommendation 9). Alternatively, sellers should be required to have licenses and purchasers should be required to obtain permits.
Sellers of sodium nitrate, potassium nitrate, nitromethane, packaged concentrated nitric acid, concentrated hydrogen peroxide, sodium chlorate, potassium chlorate, and potassium perchlorate should be required to have licenses and purchasers should be required to obtain permits. Alternatively, sales of these chemicals in some markets should be banned.
The list of chemical precursors to be controlled should be reevaluated periodically to correlate with ongoing assessment of the level of threat posed by illegal use of explosives. Bombers have demonstrated that they can change their tactics in response to the implementation of controls or shifts in the availability of particular chemicals or precursors.