It is important to be sceptical of redacted intelligence assessments, but the issues raised about Russia’s role in the 2016 US election are too serious to be dismissed so lightly

The first foreign power to interfere directly in a United States presidential election was not Russia – but France. The date of this interference was not 2016 but 1796, and the intended beneficiary not Donald Trump but Thomas Jefferson. The French ambassador in the US tried to promote Jefferson, a democrat and francophile, against the federalist and anglophile John Adams. The move backfired, and helped Adams to win.

Now, fast forward 150 years. During the cold war, and even afterwards, both the US and the Soviet Union tried, mostly surreptitiously, occasionally bloodily, sometimes successfully, to shape elections in many parts of the world. So, whatever else there is to say about Russia’s alleged involvement in the 2016 US election, do not make the mistake of saying that such a thing is unprecedented – because it is not.

Nevertheless, however you slice and dice it, Russia’s apparent involvement in America’s 2016 election is indefensible. The charge, made in a declassified intelligence report published in Washington at the end of last week by the CIA, the FBI and the National Security Agency, is a stark one. It says that Russia’s president, Vladimir Putin, personally ordered a campaign of influence in 2016 to undermine faith in the US democratic system, to denigrate Hillary Clinton and to help Donald Trump.

Russia did this, the report alleges, by both covert and overt means, including Moscow-funded hacking, trolling and other dirty work, as well as by accessing state- and local-level election arrangements, though not election counts. The report judges that Russia’s 2016 interference represents “a significant escalation in directness, level of activity and scope of effort”, and that its success signals a “new normal” that will be attempted elsewhere, notably in Europe, where the Netherlands, France and Germany all face elections this year.

This is serious stuff. It would be naive to dismiss it merely as propaganda or as fake news, or to brush it aside as the sort of thing that all governments always do – as the al-Jazeera sting on an Israeli diplomat in London, reported at the weekend, may tempt some to assert. The intelligence assessment not only explicitly denies these possibilities, but its very publication, which truly is unprecedented, is at least suggestive that the charges are solidly based.

The charges, if true, would confirm not just a state-on-state threat but a system-on-system one. They would show that the Russian state is systematically trying to subvert democratic systems, and people’s faith in them. These systems and that faith must be defended. The evidence that they are under threat should not be disregarded.

This is not to pretend that the published intelligence assessment proves its case. It doesn’t, in part because it can’t do so without compromising its sources and methods; and in part because trust in the agencies has been so shaken by events from the Iraq war to the Snowden revelations. Unfortunately, this means it leaves a space for legitimate and illegitimate scepticism alike.

Mr Trump’s response to the agencies’ assessment falls into the latter category. It was that of a candidate not that of a national leader. His dismissal of the briefing that he was given on Friday seems more concerned to reinforce the legitimacy of his own election than to address the threat from Mr Putin’s destabilisation. That’s possibly what many of his voters want to hear. “If that’s what it took, I’m glad they did it,” one Trump voter was quoted as saying of Russia’s interference.

Mr Trump’s election was dismaying, but it was legitimate. It had some lessons from which to learn. His cavalier attitude to the threat from Mr Putin’s Russia is not one of them. The Russian leader wants to weaken the democratic nations and to break public trust within them. His weapons include mendacity, demoralisation and thuggishness. It suits no one for Mr Trump to dismiss the Russian threat – except for Mr Putin.