The 206-page report outlines Russian disinformation campaigns across 19 countries. It highlights loopholes in UK campaign finance laws that might have allowed an influx of Russian money to boost the referendum. That's not to mention the propaganda from Russian-run Twitter and Facebook accounts, plus state-funded media.
"The allegations that have emerged of Russian interference prior to the Brexit referendum are all the more stunning given the innate resilience within British society to the Kremlin's anti-democratic agenda," the senators conclude in their report. "Never before in American history has so clear a threat to national security been so clearly ignored by a US president."
The latest Brexit breakdown followed a New York Times report that Trump has been more serious than previously understood about wanting to withdraw from the North Atlantic Treaty Organisation.
"Current and former officials who support the alliance said they feared Mr Trump could return to his threat as allied military spending continued to lag behind the goals the president had set," Julian Barnes and Helene Cooper report.
"There are few things that [Putin] desires more than the weakening of Nato . . . American national security officials believe that Russia has largely focused on undermining solidarity between the United States and Europe after it annexed Crimea in 2014. Its goal was to upend Nato. . . . An American withdrawal from the alliance would accomplish all that Mr Putin has been trying to put into motion, the officials said - essentially, doing the Russian leader's hardest and most critical work for him."
The two most important beacons of freedom in the world are dimming.
And just as the seas become more dangerous when lighthouses go dark, the same is true on the increasingly stormy world stage.
Will January 2019 be remembered as the month that the West came unmoored?
Previous generations had Winston Churchill and Franklin Roosevelt. Harold Macmillan and John Kennedy. Margaret Thatcher and Ronald Reagan. In 2019, there is Theresa May and Donald Trump.