Well, the Russians started with polonium, and now the Brits are shooting back with uranium.

https://questions-statements.parliament.uk/written-questions/detail/2023-03-06/hl6144

Alongside our granting of a squadron of Challenger 2 main battle tanks to Ukraine, we will be providing ammunition including armour piercing rounds which contain depleted uranium. Such rounds are highly effective in defeating modern tanks and armoured vehicles.