Yes. What’s so tricky about that?
Can a Russian, Israeli or Saudi or Mexican citizen in their respective country buy political ads targeting Americans and favoring or disfavoring a particular American candidate for office?
What if they are on vacation in the US?
What if they have jobs in the US, are not citizens, but live here and have an interest in politics?
What if they are here illegally and buy ads favoring or disfavoring a candidate for office?
What if in some cases it was their own money, what if in other cases they were hired by people in their home countries to buy ads?
What if they work in DC and act as foreign agents and pay for lobbying?
Does FB, Tw, etc. track all that?
Yes, lawfully [1]. This is a complicated area of law, which is why foreigners and foreign governments seeking to properly lobby in America hire proper counsel.
The Kochs (etc) are Americans manipulating the system with their wealth and probably within the law. I resent them for it, but that’s very different from a foreign government attempting to influence the results of a US election. I don’t pretend to know the actual pervasiveness of Russian influence; I’m only saying that your comparison falls flat.
I have to wonder if you might realize this yourself, but choose to ignore it in order to justify your own agenda.
Also, I would be angry with any outcome that was shown to be the result of election tampering. That goes for any candidate, even if I voted for them myself.