Although there is something almost quaint and amateurish about the tag “homemade,” when it applies to explosives, they can be equally as deadly and devastating as the commercially produced equivalent. The July 7, 2005, London bombers manufactured their own explosives from easily sourced and legal precursor materials. The IRA bombs that devastated London in the 1990s were mainly fertilizer-based homemade explosives (HMEs). The 1995 Oklahoma City bomb that killed 168 people contained ammonium nitrate and fuel oil (ANFO), another HME.
The prevalence of HMEs in terrorist improvised explosive devices (IEDs) is increasing. The knowledge and skills to manufacture HMEs is no longer the preserve of a few hundred expert bomb-makers. A recent Google search returned 34.5 million hits for homemade explosives. There are recipes and instructions for all types of bombs, explosives and incendiary devices, meaning that just about any disaffected adolescent can find the means to create lethal devices.
To prepare for the 1999 Columbine massacre, Eric Harris and Dylan Klebold made 99 IEDs in total. On the day they carried out this atrocity, they had planned to initiate their attack by detonating two 20-pound propane-based bombs, intending to destroy the packed cafeteria and library. Fortunately, the devices failed to detonate, or the death toll could have been much higher.
Terrorists have used HMEs for many years and for many reasons. Generally, they are relatively safe and easy for the terrorist, who may find that the risk involved in sourcing military-grade explosives is too great. When security forces and police units are effective, or have good intelligence-led search tactics, it is difficult for terrorists to smuggle in military hardware.
In May 2000, the IRA offered to place its arms “completely and verifiably beyond use” in order to negotiate a peaceful settlement. At this time, I was in Ballykinler in Northern Ireland working with a member of the Royal Ulster Constabulary’s E Department (counter-terrorist section). We were discussing the historic IRA ceasefires in relation to the recent developments. He stated, “Of course, we knew this has been coming for some time now.” I assumed he was referring to information that had been received through intelligence, and I said as much.
However, his response surprised me. He replied, “No, we’ve been turning up homemade detonators for quite some time, so we knew a ceasefire was on the cards. We’ve virtually closed down their logistics and supply, so the IRA calls a ceasefire, the government has to respond politically by relaxing security protocols and procedures, which makes it easier for them to smuggle in more arms, and so it goes on.”
Although a cynical viewpoint, it is not far from the truth and illustrates a valid point. If a terrorist organization cannot easily obtain military-grade explosives, it will improvise.
It is vital in the current world climate that police officers have a basic understanding of homemade explosives so they can identify precursor materials, offer advice on the security of such materials, and recognize activity or evidence that may mean a “bomb” factory is operating. Hertfordshire Constabulary’s Policing Serious Incidents Course educates police officers in many aspects of HMEs, not least on Exercise Vigilant, where the officers have to research their own design and construction of an IED.
During this exercise, many opportunities arise to experience how lax security is in relation to precursor materials in their local areas of responsibility. For example, bulk storage of ammonium nitrate fertilizer on a farm in Hertfordshire was taken by officers on this exercise. This provided officers with the opportunity to visit the farm while back in uniform and educate and advise the farmer on security measures.
Before the exercise, officers are taught about homemade explosives. Some of the main ones that are covered on the course are outlined below, together with common precursor chemicals used in their manufacturing.
Ammonium nitrate (AN) is manufactured or imported mainly as an agricultural fertilizer. It is also used to make commercial explosives in the blasting industry, make hobby rocket motors and in instant cool-packs (for medical use). It is cheap, stable and not subject to security legislation. This is one reason why it is favoured by terrorists.
There are a number of different types of AN explosives that, if mixed with other substances, create differing explosive effects: ANFO is AN mixed with fuel oil, i.e., diesel fuel. ANS is AN mixed with sugar. AMMONAL is AN mixed with aluminium powder. ANFOS is AN mixed with fuel oil and sugar.
Sugar chlorate is granulated or caster sugar mixed with potassium chlorate or sodium chlorate, found commonly in weed killers. HMTD (hexamethylene triperoxide diamine) is made from citric acid, hexamine and hydrogen peroxide. The ingredients are cheap, easy to obtain and plentiful. However, the explosive is very sensitive to shock, friction and heat, hence it is not commercially produced even though it yields 80% to 120% the explosive power of TNT.
TATP (triacetone triperoxide) is made from acetone, acid and hydrogen peroxide. It has similar destructive power and handling limitations to HMTD. It has been used as the main charge in many suicide attacks by international terrorists including the London bombers.
EGDN (Ethylene glycol dinitrate) is also known as nitroglycol. It is a liquid explosive produced by nitrating glycol. Glycol can be found in some antifreezes and brake fluids. It has not been encountered much outside of Israel/Palestine, however, it is mentioned in al-Qaeda manuals, and instructions for manufacturing it are available on the Internet.
As can be seen from this list, the HME ingredients are easily sourced and may appear relatively innocent to officers searching premises during routine assignments. However, even basic instruction in these explosives can make officers more aware and maybe even recognize precursor chemicals that otherwise may be missed.
Also, with some of the more volatile HMEs, for example TATP and HMTD, there is a real danger to police officers during searches. If officers cannot identify the precursor chemicals and manufacturing items, they could well be in mortal danger. If during a premises search they come across weighing scales, bottles, glass jars and filter papers, they may well wrongly assume “narcotics,” when in fact the white crystalline substance that they are swirling around in a glass jar is TATP. This action would be enough to detonate the contents, and even in small quantities, the resultant explosion could be lethal.
After this training, officers state how amazed they are by the ease with which both instructions from the Internet and the required materials can be obtained. The point is, anyone can do it. If that anyone has a political grievance or extremist viewpoint, it does not take a mastermind to work out where that leads.
Jim Dowle has worked as an operational police officer for 16 years, with a tactical firearms team, as a close protection officer and as a sniper for more than 10 years. He is now working as a trainer at the Force Headquarters. His department borders the north of London and has about 3,900 employees. He can be reached at firstname.lastname@example.org.