- [Narrator] This is Russia's TOS-1A,
nicknamed "Scorching Sun".
Its rockets produce a fiery explosion that burns so hot,
it consumes all the atmospheric oxygen in its path.
- Even if a person survives the initial blast,
the incendiary effects, the secondary fragmentation,
there is a chance that they would suffocate.
- [Narrator] Human rights advocates are pushing
for its use to be restricted.
And after Russia deployed its stock of a few dozen
against Ukraine at the start of the war,
defense experts said Ukraine's best course of action
is to find and eliminate the TOS-1A's
before Russia uses them.
(explosion booming)
The TOS-1A is a thermobaric weapon,
often referred to as a fuel air explosive or vacuum bomb.
- Which means that they mix the fuel
that is contained within the weapon with the ambient air,
and that creates the blast effect
that accompanies a thermobaric explosion.
- [Narrator] They've been used in some form
since the second World War,
like the German Naval War for rocket launcher
and American BLU-82,
which it used to clear forests in Vietnam
and against terrorist strongholds in Afghanistan.
They're designed to dislodge troops from trenches
and other enclosed spaces.
To do this, thermobaric weapons have two key components.
- The first being a combustible flammable material,
which is upon initial detonation
spread over the target area.
- [Narrator] This material seeps into crevices and holes
and anything it can penetrate.
- And then there's a secondary detonation,
which sets off the combustible material,
which has then mixed with the ambient oxygen,
and will result in a blast.
- [Narrator] As the fireball cools down,
oxygen in the surrounding area
rushes back to the detonation site,
creating a vacuum effect called negative over pressure.
Look at the difference between a thermobaric explosion
and a typical high explosive charge.
- So you can see that a high explosive,
the initial blast will be quite high,
and the pressure will then drop very quickly and dissipate.
But the thermobaric explosion,
the pressure while initially not as high
as a high explosive charge will remain high,
and expose the target for a longer duration to the pressure.
And after that, there's obviously also the over pressure
that comes back when the oxygen is depleted.
- [Narrator] Each stage can be deadly
to anyone near the detonation.
If someone survives the initial blast,
the over pressure can still give them
severe internal injuries.
- The trachea, the eyes, the ears,
and of course, after that,
when the negative overpressure comes back,
there could also be suffocation.
It's very difficult to protect yourself
from a thermobaric explosion.
The cause of how it enters everywhere
where you might expect to protect yourself.
- [Narrator] Russia has about 50 TOS-1As in its inventory,
and it's producing more.
The system can fire up to 24 unguided thermobaric warheads
in as little as 6 seconds,
covering up to 10 acres, about 7 1/2 football fields.
And because of this, Russia has used the TOS-1A
mostly as an area suppression weapon to gain ground,
and create gaps in Ukraine's defensive lines.
Because it's difficult to evade thermobaric weapons,
some military analysts have said
Ukraine's best course of action
is to try and destroy the weapons
before getting destroyed by them.
So far, it's estimated that Ukraine
has destroyed 14, damaged 2, and captured 3.
- It is quite easy for them to target these systems
once they are deployed
and once they start firing off their rockets.
The TOS-1A is to a large extent, quite a vulnerable vehicle.
They are not made to be used over a long distance.
That means that the system has to get very close
to the frontline.
- [Narrator] To take them out,
Ukraine has often flown drones directly into the vehicle,
as shown in this clip from the state run UNITED24.
But in doing so, it's also putting itself at risk.
- The subsequent explosion where the rockets
are still within the tubes would be so massive
that it could damage
a lot of the civilian infrastructure around it.
- [Narrator] Meaning, the safest place for Ukraine
to destroy the TOS-1A is out in the open
like it did in early January.
- Biggest misconception is that the weapons are banned.
- Vacuum bombs, which are banned
under the Geneva Convention.
- There are reports of illegal cluster bombs
and vacuum bombs being used by the Russians.
- [Narrator] There are two critical points
in the law of war, how a weapon is designed
and how it's used.
The TOS-1A disperses an aerosol cloud of gas,
and creates an incredibly hot fireball,
but it is not a chemical or incendiary weapon,
which are limited by law.
Because its intended use is as an area suppression weapon
and its primary effect is a blast, its design is legal.
So to use the TOS-1A lawfully,
Russia cannot cause excessive damage
that outweighs the military objective.
But due to the TOSS-1A's ability to penetrate structures,
Russia has repeatedly fired it in cities.
Some experts like Van Coller,
argue that its large area of impact
makes it too indiscriminate to be used in urban areas.
But it's unclear if and how any civilians have been impacted
by these weapons in Ukraine.
- There has been many calls for Russia
to be held accountable for the use
of thermobaric weapons in urban areas.
However, that has not taken place as of yet.
- [Narrator] The psychological impact and destructive force
of thermobaric weapons
has made them popular with numerous militaries.
As for Russia and the future of its TOS-1A...
- One has to look at the difference
between military necessity and humanity.
Of course, humanitarian law attempts to infuse
armed conflict with humanity, but at the end,
the overall objectives of states will always be met
in the pursuit of military necessity.