PS: The UK is freezing foreign assets of some Russian oligarchs... That's the UK's biggest hammer, because al the Russians put alls their money into UK real estate, laundering, banks, etc...
What the UK should do: Freeze ALL Russian assets of EVERY Duma member (they authorized Putin to invade Ukraine), EVERY Russian oligarch, EVERY Russian mafia member (that they can ascertain, or basically, every asset in valuation higher than what a regular family could afford. Which would pretty much be everything. They can sort it out later.
But if they want to get Russia's attention: that would be it.