Russia has access to a range of heavy weaponry, including 'tactical' nuclear bombs and thermobaric missile systems that can deliver devastation when used at war.
With the conflict in Ukraine intensifying, President Putin has made statements suggesting he could consider using such systems.
But what exactly are these weapons, how do they operate and what effect could they have?
Tactical nuclear bombs
These are essentially small nuclear bombs that can be used by Russia to target positions in a concentrated manner.
This differentiates them from mainstream, strategic nuclear weapons, the sort of missiles used for Britain's constant nuclear deterrent.
Because of their size and ability to create destruction on a smaller scale, they are less regulated by international treaties than standard nuclear weapons.
Militaries on all sides of the Cold War stockpiled tactical nuclear weapons, and it is believed Putin may have access to about 2,000 such devices. This type of missile has never been used in war.
Thermobaric missile systems
An alternative option for Russia is to order into action units armed with thermobaric missile systems.
These weapons, labelled 'unparalleled' by the Russian president, use their internal fuel and oxygen from the surrounding air to generate a high-temperature fuel-air explosion, the results of which can be devastating.
They cause death by turning the atmosphere around an explosion into a vacuum, literally sucking the air out of everything, including a person's lungs.
Witnesses claim to have seen Russian tracked vehicles equipped with thermobaric weapon systems in Ukraine since the invasion began.
Some have taken to Twitter sharing videos of what appeared to be tracked vehicles with these types of missiles mounted on them.
Thermobaric weapons have been used in the past. According to a UN investigation, the Syrian government used them against insurgency groups during the ongoing civil war.