Special counsel Robert S. Mueller III secured yet another indictment on Friday, hours after President Trump complained again about what he called “the Russian Witch Hunt Hoax.”

The new charges against former Trump campaign chairman Paul Manafort and a business associate, Konstantin Kilimnik, provide the latest evidence that Mueller's probe is not a “witch hunt,” as the president often describes it, but rather a steady uncovering of alleged and admitted criminal activity.

Mueller has now brought more than 100 criminal charges against 20 people. Four people, including Trump's former national security adviser Michael Flynn and former campaign adviser George Papadopoulos, have pleaded guilty.

It is getting harder and harder for the president to argue credibly that the investigation is a waste of time.

There is, however, an upside for the president in Friday's developments. The new charges against Kilimnik and Manafort, the latter of whom faces previous charges, are not directly related Trump's presidential campaign but rather are for obstruction of justice and conspiracy to commit obstruction of justice. Manafort and Kilimnik stand accused of witness tampering in Manafort's existing case, in which he has pleaded not guilty to conspiracy, money laundering, and tax and bank fraud charges related to his lobbying work for a pro-Russian political party in Ukraine and former Ukrainian president Viktor Yanukovych.

Mueller's latest legal action is a mixed bag for Trump. It weakens the president's “witch hunt” cry but does not offer any new indication that his campaign participated in Russia's interference in the 2016 election. Mueller's investigation aims to expose any such collusion, should it exist.

When Manafort was first charged, in October, White House press secretary Sarah Huckabee Sanders said the indictment “has nothing to do with the president, has nothing to do with the president's campaign or campaign activity.”

The White House did not immediately comment on Friday's new charges, but some of Trump's allies quickly picked up a familiar argument. For example, a headline on the conservative Daily Caller website read: “Mueller issues new indictment against Manafort and Ukrainian business partner that have nothing to do with collusion.”

“Nothing” is an exaggeration, however, as The Fix's Amber Phillips explains:

Besides the president or his family, there is perhaps no bigger fish in the Russia investigation than Manafort. It's not clear exactly what Manafort knows, but he does appear to be a linchpin between Trump's campaign and Russia.

He was in that meeting in Trump Tower during the campaign, the one that legal experts said may have crossed the line into conspiracy to collude with Russia. He was leading Trump's campaign as Russian meddling was ramping up. And of all the Trump campaign officials, Manafort has the most known personal and business connections to Russia.

If there was any collusion between the Trump campaign and Russia — the Trump Tower meeting with a Russian lawyer offering dirt on Hillary Clinton shows, at minimum, a willingness to collude — then Manafort might be privy to it. And as the criminal charges pile up, he could feel increasing pressure to divulge what he knows.