A video posted on YouTube shows 4 pounds of tannerite and 3 gallons of gasoline being detonated inside of a refrigerator. A March 2013 bulletin from the FBI warned that materials like tannerite, used for exploding targets, and other commercial products could provide alternative sources of ammonium nitrate and precursor material used to manufacture improvised explosive devices (IEDs).
The National Counterterrorism Center (NCTC) warned in November of last year that precursor components needed to produce improvised explosive devices (IEDs) are “widely and legally available in sufficient quantities through a variety of sources” in the U.S. and are difficult to regulate due to their legitimate uses.
Last fall the NCTC conducted a “facilitated brainstorming session” on domestic terrorism in order to identify “the most common misconceptions about conventional Homeland plotting” based on “inquiries received from Federal, state, local, tribal, and private-sector consumers and from articles published by outside experts and in the media.” NCTC analysts determined the six most common misconceptions and compared these against current analytical trends. In a bulletin detailing the NCTC’s findings, one of the most common misconceptions listed is the belief that precursors needed to manufacture improvised explosives are “difficult to legally acquire in the US without raising suspicion.” The bulletin adds that public “reporting and unclassified government assessments that highlight regulations and law enforcement ‘tripwires’ designed to prevent the acquisition of explosives precursor material give an incomplete depiction of the availability of explosive material.” In fact, the bulletin states that many of the “precursors used to construct IEDs are widely and legally available in sufficient quantities through a variety of sources because their legitimate uses hinder regulation, allowing extremists to obtain suitable amounts without attracting attention.”
Following the Oklahoma City bombing in April 1995, the U.S. government created a program to monitor the potential use of ammonium nitrate-based fertilizers in explosive devices. Since then, these law enforcement “tripwire” programs have been extended to other chemicals that could potentially be used in in the construction of explosive devices, such as hydrogen peroxide. An FBI bulletin from March says that “at least 18 incidents related to attempts to directly purchase ammonium nitrate” have been detected since 2008 because of the ammonium nitrate tripwire program, though none were found to found to be connected with terrorism. The same bulletin warns that monitoring of ammonium nitrate purchases has caused criminals and extremists to adapt, seeking “alternative commercial products containing ammonium nitrate.” Other commercially available products providing a potential source of ammonium nitrate include first-aid cold packs and exploding targets. The bulletin warns that the “FBI assesses with medium confidence criminals and extremists may actively be attempting to acquire [exploding targets] to obtain the ammonium nitrate for use in the manufacture of improvised explosives based on FBI investigations of individuals interested in manufacturing explosives.”
Other materials of concern to law enforcement include chemicals used in swimming pools and water filtration systems, beauty supply products such as hydrogen peroxide and acetone, and industrial cleaning supplies like sulfuric acid. In October 2011, the FBI and the Department of Homeland Security sent out a bulletin to police stating that “public and state and local official awareness, as well as tightened legal controls, have made it more difficult to purchase certain products that contain explosive precursors in bulk quantities or concentrated forms.” This regulation has made terrorists “more likely to use surreptitious, though legal, methods—such as multiple purchases in smaller quantities—to acquire sufficient amounts to create explosives.”