Russia has confirmed its use of thermobaric weapons in the invasion of Ukraine, according to the UK’s Ministry of Defence.

“The Russian MoD has confirmed the use of the TOS-1A weapon system in Ukraine,” the government department reported in a tweet Wednesday. “The TOS-1A uses thermobaric rockets, creating incendiary and blast effects.”

Thermobaric weapons – the term comes from the Greek words for “heat” and “pressure” – can produce much larger explosions than conventional bombs.

They contain far higher fuel concentrations than normal weapons. When the bomb hits its target, this is dispersed as an aerosol. The weapon then ignites this cloud, making a huge and powerful explosion that sucks up surrounding air and objects and is capable of vaporizing human bodies.

“It essentially produces the effect of a wall of flame about the size of a city block,” former British military chief General Sir Richard Barrons told The Times, explaining that the weapons are intended for use against large military formations like airbases.

“If it has been used against military targets it would be an escalation because it is such a big weapons system,” he said. “If it is used against civilian targets then that is a dramatic escalation.”

The TOS-1A – nicknamed “Buratino”, Russia's version of Pinocchio due to its big nose – is a multiple launch rocket system mounted on a T-72 tank. These vehicles have been a mainstay of the Russian military since the 1960s, with various modernizations and upgrades being added throughout the years.

In fact, one of the most recent developments to the T-72s is only a few days old: the 2022 invasion has seen some of the tanks fitted with improvised “cope cages” in an effort to defend against anti-tank missiles.

Despite falling foul of Ukrainian mud and missiles, the T-72’s ability to fire thermobaric weapons means it can still pose a major threat to the people of Ukraine. The impact had been “devastating,” British intelligence reports said, with Barrons telling The Times that the TOS-1A “is a weapon that is both very indiscriminate and very powerful.”

While thermobaric weapons are not banned by international law, their use against civilians is a war crime, military expert and former director-general of think tank RUSI Professor Michael Clarke told Sky News.

“It's a battlefield weapon,” he explained. “They are completely inhuman if used anywhere else - and anywhere near civilian areas.”

It would be far from the first time Russia had been accused of war crimes – not even the first time against Ukraine – and the chief prosecutor of the International Criminal Court (ICC) has announced he now intends to open an investigation into the ongoing invasion.

According to the Russian defense ministry’s Zvezdanews, which reported the use of the TOS-1A, at least 40 Ukrainians in the Chernihiv region were killed by the weapon.

“The use of thermobaric weapons would be Russia crossing yet another threshold into barbarity,” Clarke told Sky News.

“The fact is in the civilian context they are terror weapons, as well as ones that cause death and destruction.”