THE SENATE Intelligence Committee has released a bipartisan report with a stark bottom line: What President Trump calls the “Russia hoax” isn’t a hoax at all.

The fourth and latest installment in lawmakers’ review of Moscow’s meddling examines a January 2017 assessment by the nation’s spy agencies that Mr. Trump has repeatedly attempted to discredit — and confirms it, unanimously. Russia sought to subvert Americans’ belief in our democracy, bring down Hillary Clinton and bolster her rival. That these legislators from both sides of the aisle are willing to say as much after three years of thorough investigation is an encouraging sign of some independent thinking still left in government. It’s also a reminder of the peril this independence is in today.

The committee members conclude that the intelligence community produced a “coherent and well-constructed . . . basis for the case of unprecedented Russian interference in the 2016 U.S. presidential election” despite a tight time frame. The report also examines two matters of particular contention: first, whether the salacious dossier compiled by former British intelligence officer Christopher Steele played an inappropriate role in the finding of interference; the senators say it did not. And second, whether former CIA director John O. Brennan pressured colleagues into arriving at a stronger conclusion than the evidence warranted.

This latter concern is also at the center of the broad probe Attorney General William P. Barr has ordered into the origins of the Russia investigation. “There are a lot of things that are unexplained,” Mr. Barr has said. “And we’ll be able to sort out exactly what happened.” Yet the senators have pursued the same avenues of inquiry and come up with a clear answer: The differing levels of confidence among agencies were “justified and properly represented,” and the ultimate wording was reached “openly and with sufficient exchanges of views.”

The Senate Intelligence Committee deserves accolades for its clear-eyed examination of a subject that shouldn’t be political but has become polarizing thanks to the president’s provocations. Yet lawmakers wouldn’t have had a report to analyze at all if it weren’t for an intelligence community willing to dig up inconvenient truths. This is the community Mr. Trump is slowly destroying, most recently by firing his director of national intelligence and nominating an unqualified loyalist to fill the slot, as well as by dismissing Inspector General Michael Atkinson for lawfully alerting Congress about a whistleblower complaint.

The most recent Russia report is a reminder of the need to protect our elections against a repeat performance, whether by disrupting online influence campaigns, securing critical infrastructure or requiring paper trails and risk-limiting audits at the ballot box. But it’s also a reminder of the need to protect the intelligence community from co-option by a leader hostile to any truths that threaten his power.

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