The extreme lengths that Russia goes to in order to influence elections around the world but specifically including the 2016 election are well well documented. Cf the OP article.
The US can absolutely fuck up its own self governance without any outside assistance (probably actually better than most small eastern European states), but a super powerful source of outside assistance is definitely happening, in this case
@some_guy for telling what is and isn't propaganda, I recommend the RV Jones approach: Just remove from your awareness all the stuff that when you hold it up to the light and look closely, is self contradictory or obvious bullshit (which in my examinations definitely includes all the "2016 wasn't Russia" material I have seen). Everything that remains, in practice usually winds up being pretty coherent and consistent.