The Evolution Of Warfare: Fuel Air Explosives' Successors

Fuel-air explosives (FAEs) are a type of weapon that disperses an aerosol cloud of fuel and ignites it to produce an explosion. They are also known as thermobaric weapons and have been described as the most powerful non-nuclear weapons. FAEs were developed by the United States in the 1960s and used in Vietnam. They have since been used by Russia in conflicts in Chechnya and Syria, and possibly by Ukraine in the ongoing war with Russia. FAEs are particularly effective in enclosed spaces and against soft targets such as minefields, armoured vehicles, aircraft, and bunkers. They are not known to have been used since 2001, when the remaining FAE munitions were withdrawn from operational service by the US Marine Corps and Navy.

Thermobaric weapons

A typical thermobaric weapon consists of a container packed with a fuel substance and a small conventional-explosive "scatter charge" in the centre. Fuels are chosen based on the exothermicity of their oxidation, ranging from powdered metals such as aluminium or magnesium to organic materials.

The effective yield of a thermobaric bomb depends on various factors such as how well the fuel is dispersed, how rapidly it mixes with the surrounding atmosphere, and the position of the igniter relative to the container. In some designs, strong munitions cases allow the blast pressure to be contained long enough for the fuel to reach a high temperature, so that once the container bursts, the superheated fuel autoignites as it comes into contact with atmospheric oxygen.

International law does not prohibit the use of thermobaric munitions, fuel-air explosive devices, or vacuum bombs against military targets. However, their use to directly target civilians would violate the law of armed conflict (LOAC). Attempts to regulate or restrict thermobaric weapons have been made but have not been successful.

Cluster bombs

A basic cluster bomb consists of a hollow shell and then two to more than 2,000 submunitions or bomblets contained within it. Some types are dispensers that are designed to be retained by the aircraft after releasing their munitions. The submunitions themselves may be fitted with small parachute retarders or streamers to slow their descent, allowing the aircraft to escape the blast area in low-altitude attacks.

The use, production, transfer, and stockpiling of cluster munitions are prohibited by the 2008 Convention on Cluster Munitions, which has been signed by 123 states as of February 2022. However, countries like the United States, Russia, Ukraine, India, Brazil, and China have not signed the convention. Despite the controversy, cluster bombs have been used in many conflicts, including the Vietnam War, the Gulf War, the Kosovo War, the 2006 Lebanon War, the 2011 Libyan Civil War, the Syrian Civil War, and the 2022 Russian invasion of Ukraine.

Vacuum bombs

The term thermobaric is derived from the Greek words for 'heat' and 'pressure'. The weapons are controversial because they are much more devastating than conventional explosives of a similar size and have a terrible impact on anyone caught in their blast radius.

A thermobaric bomb consists of a fuel container with two separate explosive charges. This can be launched as a rocket or dropped as a bomb from an aircraft. When it hits its target, the first explosive charge opens the container and scatters the fuel mixture as a cloud. This cloud can penetrate any building openings or defences that are not totally sealed. A second charge then detonates the cloud, resulting in a huge fireball, a massive blast wave, and a vacuum that sucks up all the surrounding oxygen. The weapon can destroy reinforced buildings, equipment, and kill or injure people.

Thermobaric weapons have a much more rapidly expanding blast than a conventional explosion. This is because fuel-air weapons take time to distribute the aerosol explosive widely before ignition.

The TOS-1A, a Russian thermobaric rocket launcher, has been used in Ukraine. The TOS-1A uses thermobaric rockets, creating incendiary and blast effects. The Russian military calls the units "heavy flamethrowers", which can fire rockets up to 9km.

Thermobaric weapons are not incendiary weapons as defined by the Convention on Certain Conventional Weapons (CCW), a treaty ratified by both Russia and Ukraine that regulates the deployment of incendiary weapons. While they depend on a chemical reaction, they are not “primarily designed to set fire or cause burn injuries”. Instead, thermobaric weapons are primarily designed to generate blast and pressure. While flame and heat are employed as the most efficient way to generate that blast and pressure, thermobaric weapons are not primarily designed to set fire or cause burns. Burns to persons are an incidental effect, and thus thermobarics are not properly categorized as incendiary weapons.

Thermobaric weapons are also not inherently indiscriminate. Inherently indiscriminate weapons are those that, by their nature, are incapable of complying with the principles of distinction and proportionality. Vanishingly few weapons fit into this category. Given that the International Court of Justice (ICJ) has not branded nuclear weapons, with their uniquely awful characteristics, as inherently indiscriminate, thermobaric weapons are almost certainly not per se unlawfully indiscriminate.

Aerosol bombs

The term "thermobaric" comes from the Greek words "thermo" (heat) and "barikos" (weight, pressure). These weapons are controversial because they are significantly more powerful than conventional explosives of a similar size and can have devastating effects on anyone within their blast radius.

The TOS-1A, a Russian thermobaric rocket launcher, is an example of a large-scale aerosol bomb. It can fire rockets up to 9km away and has been used in Ukraine, according to the UK's Ministry of Defence.

There are no international laws specifically banning the use of aerosol bombs, but using them against civilian populations in built-up areas could be considered a war crime under the Hague Conventions of 1899 and 1907.

Volumetric weapons

The effects of volumetric weapons are compounded in enclosed spaces, making them highly effective in buildings. They are likely to cause civilian casualties due to their indiscriminate and uncontained nature. The fuel-air explosive is described as "just another way of killing people in ways that leave bodies that are horrifying to look at," by Dr. Theodore Postol, an MIT physicist and missile expert.

Thermobaric weapons are a subclass of volumetric weapons and are commonly known as fuel-air explosives, vacuum bombs, or enhanced blast weapons. They are filled with aerosolized solid fuel or a highly combustible slurry. Once they reach their target, an initiating explosion or "scatter charge" spreads a cloud of fuel across the target. Milliseconds later, a secondary combustion causes the cloud of fuel and atmospheric oxygen to detonate, resulting in a massive fireball that produces an especially powerful blast wave.

Thermobaric weapons have been developed and used by several countries, including Russia, China, the United Kingdom, and the United States. They have been used in various conflicts, such as the Vietnam War, the Syrian Civil War, the conflict in Ukraine, and the Russo-Chechen Wars.

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