In light of the ongoing investigation in New York City, DHS and the FBI believe it is prudent to remind our state and local partners about the variety ofdomestically-available materials that could be used to create homemade explosives, which have been utilized in previous terrorist attacks.

(U//FOUO) Evidence from police investigations, foiled plots, and past terrorist attacks reveals terrorists have used commercial storage facilities, including self-storage units, to store explosives or other supplies prior to attacks. These facilities afford flexibility and some degree of cover to terrorists engaged in preoperational activities, and can be used to hide explosives and other materials with limited risk of arousing suspicion. With good operational security, terrorists can circumvent restrictions on the types of materials allowed in facilities. DHS and the FBI recommend that law enforcement establish contact with storage facilities to encourage self-storage facility employees, operators, and owners use systematic procedures for detecting and reporting signs of suspicious behavior.