(CNN) Friday's news that special counsel Robert Mueller had announced indictments against 13 Russians for their alleged roles in a massive -- and complex -- attempt to influence the outcome of the 2016 election is a major moment in the investigation.

It marks the point at which no sane person can dispute this basic fact: Russia actively sought to interfere in our election in support of Donald Trump.

Most people have long believed that as fact -- largely because the US intelligence community has unanimously agreed on that fact for much of the last year.

Donald Trump is not most people. He has repeatedly left open the possibility that Russia wasn't responsible for the election interference, suggesting China or even a "guy sitting on his bed who weighs 400 pounds" might be behind it.

For Trump, acknowledging Russia tried to meddle in the 2016 election to help him is tantamount to acknowledging that he didn't win fair and square. Of course, it isn't.

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