Britain says the Russian Ministry of Defense has confirmed the use in Ukraine of the TOS-1A weapon system, which uses thermobaric rockets.
"The Russian MoD has confirmed the use of the TOS-1A weapon system in Ukraine," it said on Twitter. "The TOS-1A uses thermobaric rockets, creating incendiary and blast effects."
Thermobaric weapons, sometimes called "vacuum bombs," basically suck in oxygen from the surrounding air to generate a more high-temperature explosion than conventional bombs.
Though not illegal, their usage is controversial because they are much more devastating than conventional explosives of a similar size, and have a devastating impact on anyone caught in their blast radius.
The United States has used them in Vietnam and more recently in Afghanistan to destroy mountain caves where militants were hiding.
Russia used them in its war in Chechnya in 1999 and was condemned by Human Rights Watch for doing so.
Russian-made thermobaric weapons were also reportedly used in the Syrian civil war by the regime of Bashar al-Assad.
Britain Says Russian Defense Ministry Admits Using Thermobaric Weapons In Ukraine
A TOS-1A weapon system, which uses thermobaric rockets, also know as "vacuum bombs." (file photo)