Recall that part of the negotiations with Iran involved releasing the money in the banking system that the USA had frozen. (Not, as some Fox-ish commentators suggested, “paying” them American money). But since the US had a throttlehold on the banking system, the Iranians rghtly so did not trust them, and so demanded cash… pallets of it.
The problem is not so much lawsuits. They happen anyway, anywhere, unless the government controls the judicial process and says “no”.The problem is getting them enforced in another jurisdiction.
I presume, should the Western countries decide Russia must pay Ukraine, there’s not much the Russians can do about it if their money is within the grasp of the governments of the West. OTOH, there was an article recently about how the Russian government was essentially seizing the assets - in Russia - of western companies leaving Rssia following sancctions.
The economy has always been a weapon.