IN January 1984, Soviet KGB spooks reaffirmed a priority that was set by the Kremlin after the second world war. “Our chief task is to help to frustrate the aggressive intentions of American imperialism…We must work unweariedly at exposing the adversary’s weak and vulnerable points.” As Vasili Mitrokhin, a KGB archivist who defected to the West with a large number of KGB files, explained, “exposure” in the parlance of the KGB meant disinformation fabricated by service A, the active-measures branch of the First Chief Directorate of the KGB. This unit was charged with foreign disinformation, which it spread through a network of officers outside Russia.

At the height of the cold war, service A numbered some 15,000 officers who engaged in psychological warfare and disinformation. Their operations included planting stories about John F. Kennedy being killed in a secret CIA plot, AIDS being a virus developed by the Pentagon and sending fake letters from the Ku Klux Klan to the Olympic committees of African countries. “We are opposed by a monolithic and ruthless conspiracy that relies primarily on covert means for expanding its sphere of influence,” Kennedy warned in 1961, “on infiltration instead of invasion, on subversion instead of elections.” In 1968, in an attempt to head off the election of Richard Nixon, the Kremlin offered to subsidise the campaign of his Democratic rival, Hubert Humphrey. (Nixon’s impeachment over Watergate caused dismay in the Kremlin, which used dirty tricks and eavesdropped on journalists as a matter of routine).

In November 1984 the Kremlin tried to stop Ronald Reagan from being re-elected. As part of its active-measures programme, Moscow promoted the slogan “Reagan Means War!” To discredit him, Russia propagated stories about Reagan’s militaristic adventurism, rising tensions among NATO allies, discrimination against ethnic minorities and corruption. In the end, Reagan won a landslide victory, exposing the limits of Soviet power. A student of the Andropov Academy, Vladimir Putin would almost certainly have undergone training in active measures. In a book of interviews, Mr Putin described how he used these techniques against dissidents at home, spoiling and hijacking their events.

It is hardly surprising that Mr Putin—who used disinformation in his war against Ukraine, who has targeted European countries, including Germany, who uses cyberweapons against his enemies in Russia—should try backing Donald Trump, who ran against establishments of all stripes, by hacking into both parties’ computers but only leaking Democratic e-mails to the media. What is probably more surprising, to Mr Putin at least, is that Mr Trump actually won. Firmly convinced that all elections get rigged one way or another, he might also have been surprised by the government’s inability to fix the vote in Hillary Clinton’s favour.

But if Russian interference to boost Mr Trump is now beyond doubt, this does not mean that Russia caused his victory. “While the correlation is clear, the causation is not,” says Peter Pomeranzev, an expert on Russia’s disinformation. Had Mr Trump lost the election, Russian active measures would have been deemed no more successful than those of the Soviet KGB in 1984. By blaming Mrs Clinton’s defeat on Russia, her allies risk echoing Mr Putin’s allegations that a wave of protests against his third presidential term in 2012 were the result of an American conspiracy.

The main reason Mr Putin appears a victor in America as well as in Europe, where nationalism is on the rise, is that he identified right-wing populist movements as potential winners from the start. But it is Mr Trump’s affinity with Mr Putin, rather than Russia’s active measures, that helped him win. As George Kennan, a diplomat, observed in 1946, the ability to rebuff Russia’s disinformation, “depends on health and vigour of our own society. World communism is like a malignant parasite which feeds only on diseased tissue”. There were enough American voters who, like Mr Trump, believed that the country is a “hellhole, and we’re going down fast”. Mr Putin no doubt agrees.