Soppose a country has some money or other assets in foreign countries or banks or whatever, and gets overthrown in a revolution. Say for example Saudi Arabia or one of the other oil-rich middle-eastern countries (or China, for that matter). And assume that some remnant of the original government does not recognize the validity of the revolution and still claims to be the legitimate rulership of that country.
What do the banks or other custodians of the money/assets do about it, and what decides who they recognize as the owners of these assets? Does it depend on who their government officially recognizes? Or does it get fought out in the courts? (If so, is the local courts - who would presumably rule in favor of the current government, or the courts of the country where the assets are?) Or do the banks/trustees get to decide what they want?
Depends on what the local government (Switzerland, USA, Britain, etc.) feels about the change of government. Presumably if you are a Swiss bank, your definition of “Government of Saudi Arabia” is whatever is the Swiss government’s current definition. Most likely, things will be frozen until the dust settles.
Also, the new government, if it has standing, typically finds and asks the foreign banks to freeze the accounts of the former Sheik/Shah/President-for-Life etc. until they can ascertain if the funds have been stolen, in which case they launch legal proceedings to recover them.
Of course, this requires cooperation. Hence, the need for the new government to be recognized.
The problem is, if you have skipped the country and have $700M in Swiss accounts, and it is only a matter of time before the new government is recognized - what do you do to prevent your funds from being seized? I suppose you have to transfer them to a new country tout suite and gamble it won’t cooperate. The number of safe havens is limited, especially if the USA is the one helping to apply the pressure.
That’s not because of any dispute over who is the legitimate government of Iran, though, but because of a dispute over the liabilities of the state of Iran to the US.
In general, the answer to the OP’s question is that it’s not the business of (say) the US to determine who has the right to govern (say) Saudi Arabia. Unless the question is distorted by domestic US political considerations (which of course it often is) the US takes the view that the government of country X is whatever outfit actually governs country X; that’s what “government” means. So the right to control the sovereign assets of country X located in the US - bank deposits, say - belongs who whoever actually runs country X, which is a question of fact. If, on the facts, it’s unclear - there’s a civil war going on, or a general collapse - then the assets may be frozen until someone can show they are in control. But the US will very much try to avoid getting involved in decreeing who ought to be in control, and giving them control over the assets concerned.