So in this case. First it was FB telling everyone how someone in Russia bought ads on Facebook for election. Reddit's /r/politics happily started a thread how this is finally the evidence that proves all these allegations. So ok, let's wait to see what's there. Expected some alt-right, KKK, white supremacist ads, but ended being pro-Hillary and Black activism instead. But of course, that didn't phase the political analysts so now this is also an evil cunning plan to overthrow democracy here and so on and there are Russians hiding in the bushes pulling strings. Heck, it could have been ads about eating more potatoes and political analysts at these news organization would have found a way to turn that into a conspiracy story just as well.
How much was spent on these adds, how many hundreds of millions? Oh just $100k. Given the importance of US elections, I would expect every country which has money to spare to try to influence the results in some way to benefit itself. Did the Chinese buy ads, the French? I'd say they'd be silly not to.
Without hypotheticals, here is Qatar giving a $1M birthday "gift" to Bill Clinton:
https://wikileaks.org/podesta-emails/emailid/8396
Now that's some interesting foreign influence worth talking about