There is no textbook on what to do. The US has a history of meddling in other countries’ politics during the cold war — and since. But Russia’s thinly-disguised intrusions into the 2016 election is the first time the US has clearly been the object of such attention. Moreover, the Russian bear is pushing at an open door. All Vladimir Putin needs to do to cause trouble is to sow doubt about the integrity of the US electoral process. Large numbers of Americans already suspect the November result will be rigged. So does Donald Trump, who is the first US presidential nominee to invite a foreign power to leak material that would damage his opponent. If ever US democracy was vulnerable to skulduggery that time would be now.

What chance does it have of succeeding? To some extent it already has. In a Bloomberg interview last week, Mr Putin offered a blatant non-denial denial that Russia carried out the recent hacking episodes. “To do that you need to have a finger on the pulse and understand the specifics of domestic political life in the US,” he said with a knowing smile. “I’m not sure that even our foreign ministry experts are sensitive enough.” The Russian president might as well have winked at the camera. Nobody, from the cyber security firms looking into the hacking of US political outfits, to the FBI, which is investigating them, doubts Russian intelligence agencies were behind the breaches.

Nor is there much question about motive. The email trove hacked from the Democratic headquarters showing insider bias for Hillary Clinton over Bernie Sanders, was leaked on the eve of Mrs Clinton’s convention in July. It inflamed Mr Sanders’ supporters, many of whom already thought Mrs Clinton had rigged the primaries. Last week Julian Assange, the holed up founder of WikiLeaks, which released that first batch of emails, promised there would be more to come before November. “It is not a question of whether Russia leaks more data but when,” says Dmitri Alperovitch, co-founder of CrowdStrike, one of the largest US cyber security companies. Mr Assange, who is Russia’s preferred data dump, promises “teasers” in the next few days.