The most secure elections are ...

The most secure elections are not having any elections at all. They are not necessary for democracy. In fact elections are the sign of an oligarchic system: It is much more democratic to select political leaders by lot (as the ancient greek and inventors of democracy did):

How to Putin-Proof Your Elections

Russia has been meddling in Western democracies and their internal affairs since at least 2014, but the issue came to the fore only after the 2016 US