Brian Klaas is a fellow in comparative politics at the London School of Economics. He is the author of "The Despot's Accomplice: How the West is Aiding & Abetting the Decline of Democracy." The opinions in this article belong to the author.

(CNN) In the past week, three senior White House staff members have either been fired or resigned. The staff shake-up, which ended with Gen. John Kelly being appointed as President Trump's new chief of staff , was supposedly done to impose a new level of discipline to a presidency that has been derailed by chaos, scandal and a complete lack of major legislative achievements.

Unfortunately, a staff shake-up won't solve the problem in the White House . That's because the problem in the White House is Donald Trump.

That unfortunate truth was made crystal clear Tuesday when Politico published a full transcript of President Trump's July 25 interview with The Wall Street Journal from the Oval Office. The interview transcript is, frankly, bizarre -- and includes many incoherent, rambling statements that do not make sense.

It's an alarming read, particularly when you remember that the person who is struggling to speak authoritatively or coherently on virtually any topic is the same person that is in charge of America's military might and its nuclear launch codes.

There are three main takeaways from the interview.

First, Trump has, at best, an extremely thin understanding of every major policy issue, from health care to tax reform. When pressed for any details, Trump retreats to empty platitudes and deflects by saying: "We'll see what happens."

Second, the interview is a window into a mind that is singularly obsessed by his election victory last November -- which took place 268 days ago. Repeatedly, Trump is stuck in a distant past that he perceives to be glorious, which is distracting him from creating a better future for America.

Third, Trump makes demonstrably false statements with incredible frequency -- even about trivial matters.

His casual relationship with the truth, as though it's a pesky but disposable annoyance, has destroyed the credibility of the White House in just six months.

JUST WATCHED Cooper: WH misleading over Trump Jr. statement Replay More Videos ... MUST WATCH Cooper: WH misleading over Trump Jr. statement 04:07

Let's take a closer look at the key takeaways from this strange interview, with direct quotes from the President himself.

The reporter asked Trump several policy-related softball questions -- questions that any normal politician would hit out of the park with ease. Trump's responses whiff instead, meandering around the question nonsensically without answering it. His response to a basic question (What are the main goals of your tax plan?) starts like this:

"I want to achieve growth. We're the highest-taxed nation in the world, essentially, you know, of the size. But we're the highest taxed nation in the world [note: this isn't true]. We have -- nobody knows what the number is. I mean, it used to be, when we talked during the debate, $2.5 trillion, right, when the most elegant person -- right? I call him Mr. Elegant. I mean, that was a great debate. We did such a great job..."

This doesn't make sense. This would fail an elementary school test for lack of clarity, non sequiturs and rambling incoherence. But beyond the hard-to-follow twists and turns of this answer, the interview also shows an astonishing shallowness to his understanding of enormous policy debates. He repeatedly makes mistakes when he does provide detail, but most of the time he steers clear of detail and retreats to safer ground he knows well -- his election victory.

When asked if he hopes to work with Democrats in Congress to pass a bipartisan infrastructure bill (which Democrats have indicated they are willing to work on with President Trump), his response begins as follows:

"Well, they tried -- they tried it with me. She spent hundreds of millions of dollars on negative ads. She didn't do a positive ad, virtually. And she lost easily, you know, 306 to 223 I think, right, -- 223 something like that."

The question was about infrastructure. It was about bipartisanship. Trump turned it into an opportunity to discuss his defeat of an election opponent last November. Imagine if President Barack Obama had fixated on beating John McCain in August 2009. It would have been perceived as being unhinged, because it is. And yet, time and again, Trump singularly fixates on the election, mistaking the starting gun of his presidency for the finish line.

Finally, Trump lies or misleads in the interview repeatedly, even about matters that are completely inconsequential to anyone in the country other than Donald Trump. For example, when asked about the controversial speech he gave to the Boy Scouts (in which he thanked children for voting for him before regaling them with the story of a hot cocktail party in New York) Trump claimed that the head of the Boy Scouts called the President to tell him that "it was the greatest speech that was ever made to them." The Boy Scouts appeared to deny that any such call took place and went so far as to publicly rebuke President Trump for his highly-politicized speech at an avowedly apolitical event for kids.

The falsehoods -- or outright lies -- peppered throughout the interview add to the latest exposed lie from the Trump camp, as it is now clear that President Trump was directly involved in crafting a deliberately dishonest statement about Donald Trump Jr.'s meeting with Russians, offering compromising information on Hillary Clinton during the campaign. This revelation comes despite vehement denials from the White House and the President's own lawyers.

The credibility of the White House matters. Trump has willingly sacrificed it, tossing it away for no reason, to boast about matters as a trivial as a speech to Boy Scouts. The loss of credibility for America's President will have serious consequences, both for Trump's domestic agenda and for the standing of the United States in the world. It's not an amusing matter.

This latest rambling interview is yet another window into the White House. It makes clear that the recent staff changes will do little to rescue the Trump presidency, because the real problem with the Trump presidency starts at the very top.