It's a well known fact that Vladimir Putin has long held a grudge against America in general, and Hillary Clinton in particular.
This morning's New York Tines contained a LENGTHY article (a touch over 10,000 words) about the extent of Russian meddling in our 2016 presidential election. It's worthwhile to set aside some time, and read as much of it as you can. Trump, naturally, would call it all "fake news", but it is very obvious that it is anything but.
https://www.nytimes.com/interactive/2018/09/20/us/politics/russia-interference-election-trump-clinton.html?action=click&module=Top%20Stories&pgtype=Homepage