(CNN) Up until this week, Donald Trump could say, with some veracity, that the special counsel investigation into Russia's attempted meddling in the 2016 election and potential collusion with his campaign hadn't produced a single tangible result.

After this week, Trump can't make that claim. Or anything close to it.

When we look back at the long arc of Russia's interference in last year's election, the past four days will stand out as the week that the special counsel investigation led by Robert Mueller got very real for President Trump and his political inner circle. This will be the week that this all went from a theoretical discussion of who did what wrong when and who knew what when to a deadly serious endeavor with potentially long-running impacts not just on Trump's administration but the nation more broadly.

From the indictment of former Trump campaign chairman Paul Manafort on Monday to the forgetfulness of Attorney General Jeff Sessions revealed on Thursday, this week was a seminal one.