US Law (specifically the Federal Election Campaign Act) generally tries to prohibit foreign nationals from donating to political campaigns.
It seems like that act has some pretty broad restrictions: "The Act prohibits knowingly soliciting, accepting or receiving contributions or donations from foreign nationals. In this context, "knowingly" means that a person:
...
Is aware of facts that would lead a reasonable person to inquire whether the source of the funds solicited, accepted or received is a foreign national."
So a candidate could be taking a legal risk if he took a large donation from a foreigner and his excuse was that he didn't realize who the donation was from and wasn't interested enough to find out who was making the donation.
But I don't really think the US has decent enough disclosure laws for political donations or enforcement of current laws to adequately prevent or prosecute foreigners donating to political campaigns.
well to get around that one well known campaign simply made sure the donations from "unknown" sources were sufficiently small and diversified in identifying data so they would not be reported/flagged.
the current political parties set up the donation game so they could work it to their advantage and eliminate possibility of a 3rd or more parties.
Is it actually illegal for the actual Russian government to buy advertising on Facebook/Google linking to influential material? Not being condescending but actually asking this. Facebook can easily terminate the ads but does the US gov’t have this as illegal?