THE CACOPHONOUS and frequently confusing debates over the Russia investigations by special counsel Robert S. Mueller III and several committees of Congress tend to obscure some big and virtually uncontested truths: that the regime of Vladi­mir Putin intervened in the 2016 election with the intention of harming U.S. democracy; that it will almost certainly seek to do so again; and that there has been no concerted effort to defend the country from this national security threat.

We say "virtually uncontested" because the principal dissenter from this consensus, which unites U.S. intelligence agencies and a large bipartisan majority in Congress, is President Trump — who continues to shove away the conclusive proof about Russia's actions compiled by American intelligence professionals and to obstruct efforts by his Cabinet and staff to respond to them.

A comprehensive report by Post reporters Greg Miller, Greg Jaffe and Philip Rucker contains dismaying evidence of the resulting dysfunction. Mr. Trump has never held a Cabinet-level meeting on the Russian intervention or on how to prevent its recurrence. At the National Security Council, it is understood that to bring up the Russian threat is to risk enraging the president. The same goes for the CIA officials who conduct Mr. Trump's daily intelligence briefing; they sometimes leave material on Russia out of the oral session, so as not to send the session "off the rails," in the words of a former senior official.

The reasons for Mr. Trump's denialism, like those for his curiously obsequious public treatment of Mr. Putin, are disturbingly unclear. His aides cast it as a matter of egotism, a refusal to accept that his electoral triumph was the product of anything other than his own talents. Mr. Mueller and the congressional committees are investigating whether the president or his campaign actively colluded with Moscow or whether the president has other compromising ties with Russians. So far, no conclusive proof of such connections has surfaced.

What is clear is that, whether out of venality or vanity, Mr. Trump is failing to protect the country against a serious threat. Ensuring that future elections are not compromised requires comprehensive action across the government; former CIA director Michael V. Hayden, who served under President George W. Bush, compared it to the response demanded by the Sept. 11, 2001, attacks. State election systems, many of which were probed by Russian cyberattackers, must be hardened; social media platforms must be pushed to erect protections against propaganda shoveled by armies of bots. Most importantly, Mr. Putin's regime must be effectively deterred, which will happen only if he concludes that the potential costs of interference are greater than the gains.

For now, the opposite is true, according to The Post's reporting. Attorney General Jeff Sessions testified in October that not only is the administration not doing enough to stop Russian interference, but "we are not able to fully grasp the technical dangers that are out there." Meanwhile, intelligence from inside the Kremlin indicates that Mr. Putin believes he has pulled off one of the greatest covert operations in history, one that was "more than worth the effort," as one U.S. official put it.

Mr. Trump is still intent on restoring good relations with Mr. Putin rather than fighting a threat he refuses to believe in. To cover up his past actions, or satisfy his ego, he is exposing the American political system to unacceptable danger.