I've wondered about that question. Germany is not at war with Russia, Gazprom is a publicly traded company, and there are international courts that arbitrate such matters and could yet find the German government at fault. My non-lawyerly gut feeling is that, for better or worse, the trend of the last 30 years has been that the international mechanisms for enforcing contracts and property rights are now the strongest force in the legal universe, stronger than sovereignty and in some cases even human rights.