Analysis by Chris Cillizza, CNN Editor-at-large

(CNN) -- President Donald Trump had a golden opportunity on Monday to stare down Russian President Vladimir Putin and tell him, in no uncertain terms, that Russia's meddling in the 2016 election was totally unacceptable, and that if anything like it continued going forward, there would be major and serious penalties to pay.

Instead, standing next to Putin at the US-Russia summit in Helsinki, Trump did the opposite.

"I hold both countries responsible," Trump said in response to a question from the American press about Russia's interference. "I think that the United States has been foolish. We've all been foolish. We're all to blame." He went on to deride the FBI, special counsel Robert Mueller's investigation, the US intelligence community,

I mean, WHAT? W-H-A-T?

Make no mistake what happened in Finland on Monday: An American President -- contrary to the unanimous findings of his intelligence community and the Republican-led Senate Intelligence Committee -- sought to split blame with a foreign adversary who actively interfered in an American election to help him and hurt his opponent. And he did so while standing next to the Russian President -- a man who heads a country that not only sought to sway the 2016 election through interference but also invaded and annexed Crimea and allegedly poisoned a former Russian spy and his daughter on British soil.

It was the most stunning moment yet of a presidency filled with them. (On a domestic scale, his "both sides" response to the racially motivated violence in Charlottesville was equally stunning, but Monday's summit sets a new bar for the global implications of Trump's actions.) Not only has Trump actively worked to realign geopolitics with his attacks on the European Union and NATO but, as of Monday, he made clear that he trusts Putin at least as much -- and maybe more -- than his own intelligence officials.

Asked directly how he reconciled the intelligence community's conclusion that Russia had meddled in the election with Putin's denials, Trump punted -- saying both sides made good points and believed their view strongly. Putin was "extremely strong and powerful in his denials," said Trump. What clearer evidence could you ask for that Trump sees Putin as just as credible as the AMERICAN intelligence community?

I mean, Putin denied he meddled in the election strongly. So we have to believe him, right? RIGHT???

It's impossible to accurately describe how remarkable that sort of equal footing is when it comes to recent US relations with Russia -- particularly as seen from the Republican point of view. Prior to Trump's ascendancy, Republicans had spent the better part of the last four decades casting Russia as a savvy and dangerous enemy. Ronald Reagan famously described the Soviet Union as a bear -- insisting that America needed to be as strong and powerful as Russia as quickly as possible. In the 2012 campaign, Mitt Romney, to some mockery from Democrats, said that Russia was America's No. 1 geopolitical foe.

"There's no question but that in terms of geopolitics -- I'm talking about votes at the United Nations and actions of a geopolitical nature -- Russia is the No. 1 adversary in that regard," he told CNN's Wolf Blitzer.

The gulf between that sort of rhetoric and what we saw on Monday in Helsinki is as wide as the Grand Canyon. In fact, the difference between Trump's treatment of Russia and Putin and that of his party isn't even the stuff of an intraparty disagreement. It's a disagreement on fundamental principles. It's as though Donald Trump was pro-abortion rights and his party opposed abortion rights. Oh wait ...

The reaction, as you might expect, watching what can only be described as a jaw-dropping performance by the President of the United States was immediate and hugely critical.

"Donald Trump's press conference performance in Helsinki rises to & exceeds the threshold of 'high crimes & misdemeanors,'" tweeted former CIA Director John Brennan. "It was nothing short of treasonous. Not only were Trump's comments imbecilic, he is wholly in the pocket of Putin. Republican Patriots: Where are you???"

Former Illinois Republican congressman and conservative talk radio host Joe Walsh voiced a similar sentiment. "This press conference is an absolute disgrace," he tweeted. "Trump won't even side with America. What Trump did today was commit treason. He cannot be supported anymore. He is a clear & present danger to America. Republicans can no longer be quiet. I won't be quiet. I am done with him."

There may be a tendency in some circles -- primarily occupied by Trump allies who believe whatever he says -- to cast the sorts of reactions from Brennan and Walsh as just the carping of losers, people who disagree with Trump or who he beat. Sore losers. Haters. Libruls.

Don't fall for it. Trump's decision to throw over the conclusions of his intelligence community (and the Senate Intelligence Committee) because Putin says he didn't meddle in the election has ZERO to do with partisanship. This isn't about Democrats and Republicans. It's about Americans and Russians. Or maybe more accurately, it's about western democracy versus a Russian leader who has made destabilizing the West a long-term goal of his.

Why is President Trump unable or unwilling to see that reality?

Yes, there is the possibility that the Russians have something compromising on him, something he is so embarrassed about that he is willing to ignore the clear and present danger posed by Russia to keep it from going public. Putin denied the existence of any sort of "kompromat" on Trump in the news conference Monday, arguing that he didn't even know Trump was in Moscow for the Miss Universe pageant in 2013. To which I would say: Ask yourself if a former KGB official who is now the president would be unaware of someone as wealthy and high-profile as Trump being in his country. I mean, come on.

Unless and until we find out about whether "kompromat" on Trump actually exists -- and what the compromising information is -- I think the clear motivation for Trump's stunning performance on Monday is his total and complete inability to see beyond his own self-interest.

In Trump's mind, any talk of Russian interference in the election is an attempt to undermine the "brilliant campaign" (his words) he ran in 2016 and somehow invalidate his victory. Why else would Trump launch into an extended riff about his Electoral College margin in front of the President of Russia and almost two years removed from that election? What does Putin care how many electoral votes Trump won? And what difference does it makes anyway? Trump is President. He won. The end.

Conservative pundit Brit Hume summed up Trump's remarkable blindness to anything beyond his own nose in this tweet: "Because Trump is unable to see past himself, he sees the Russia meddling investigation as only about him and the collusion claim, and thus calls it a witch hunt. But the investigations are much more about what Russia did, as the House and Senate reports long since established."

Not everything in the world is about Donald Trump.

Attempting to get to the bottom of the meddling of a foreign power in a US presidential election isn't about trying to hurt Trump. It's way, way, way bigger than that. It's about trying to protect democracy from those who would tear it down from the inside out. A President who can't or won't see that is someone who is actively dangerous not only to the United States but to the world.