https://theintercept.com/2016/08/03/citizens-united-foreign-money-us-elections/
is actually a 4-part series of articles (maybe more to come)
one part explains more about US law, makes it clear if a foreign corp.
(or foreign
government via a corporation created for that purpose) wanted
to spend, say, $100 billion to influence US elections, that would be legally
ok if it did it in various ways, such as via contributions to
the US "chamber of commerce" or Karl Rove's "crossroads GPS."
And these things are happening, we just do not know how much.
Another notes that the US ambassador to China under Obama, Gary Locke,
wanted to sell his house in Washington DC and hadn't managed to do so
after several months; then the same Chinese tycoon who gave Jeb Bush
forces over $1 million conveniently bought it for $1.7M. Just yet
another typically completely corrupt "entirely legal" transaction, the
fact Locke happened to be ambassador was "pure coincindence"..., only
difference from usual USA corruption is that this time foreigners
involved.