The Russia report shows we have a security problem. He lives in No 10

If it walks like a duck and talks like a duck, is it a duck? Or, more pertinently, at the moment, if Boris Johnson acts like a Russian asset and talks like a Russian asset, is he a Russian asset?

This isn’t a cute Johnsonian provocation. An “asset” in intelligence terms is not necessarily someone who actively works for a foreign state. It’s someone who’s used by a foreign state. It’s someone who acts – knowingly or unknowingly – to further that state’s interests.

I’m not making allusions to Johnson’s meeting at an Italian palazzo with the former London KGB chief weeks after Russia had released a chemical weapon on Britain’s streets, which I reported on last autumn, as gobsmacking as that was. Or his relationship with Alexander Temerko, a Russian oligarch, who happens to both try to influence Tory policy and give the party money. Because Johnson almost certainly does only what is in Johnson’s best interests.

It’s just that in the case of Russian interference in our elections, and specifically the EU referendum, Johnson’s best interests are Russia’s best interests. And it was in both of their interests last week to disregard the findings of the report published by the intelligence and security committee (ISC).

Related: PM accused of cover-up over report on Russian meddling in UK politics

“This is about pressure from Islington Remainers who had seized on this report to try to give the impression that Russian interference was somehow responsible for Brexit,” Johnson said, in response to a question that had nothing to do with Brexit.

It doesn’t matter why Johnson who, until 2016 was an Islington Remainer, made these remarks. Or what motivated him or what he seeks to gain from them. But by politicising a report from the ISC he has done something dark and dangerous. Because the ISC does not act like other committees. It is scrupulously non-partisan and proudly independent. The findings of the report were endorsed by its current and previous Conservative chairs. And to reject its findings is not just a foreign policy win for Russia – and all other states that could benefit from interfering in our elections – it’s a fork in the road for Britain, the parliamentary democracy.

“This committee has been subject to unprecedented delay and dislocation,” Julian Lewis, the committee’s new chair, said on Tuesday. “This must never happen again.” But what can be done to prevent it? Nothing.

What did Johnson know, when? What role did he play in MI6’s lack of action? Is he negligent? Is he complicit? And will someone ask Sir Alex Younger, the head of MI6? Because in December 2016, a month after the US election, he made a rare public speech. The internet had changed everything, he said, and the “connectivity at the heart of globalisation” had created a “fundamental threat to our sovereignty”. It was a warning. But to whom? The prime minister, Theresa May? Or his boss? Boris Johnson.

It took nearly a year for any kind of response at all. Then, in November 2017, May made a landmark speech: “Russia, we know what you are doing,” she said.

The timing of this was not an accident. It was two weeks after the first of Robert Mueller’s indictments were unsealed. Many threads of his investigation ran through London. The Russian ambassador was a key conduit between the Trump campaign and the Kremlin in the summer of 2016, when Johnson was foreign secretary. And WikiLeaks, based in London’s Ecuadorean embassy, was revealed to be “Organisation A”, a channel for Russian intelligence. It was no longer credible to ignore British involvement in a transatlantic web of Kremlin-influenced operations.

And yet that’s exactly what we did. That’s the revelation of last week. “In stark contrast to the US handling of allegations of Russian interference in the 2016 presidential election,” the report notes, “where an intelligence community assessment was produced within two months.” Hundreds of FBI agents, lawyers and prosecutors worked for more than three years on Mueller’s investigation in the US. Here, on the other hand, when asked by the committee for its assessment on Russian interference in the referendum, MI5 initially handed over six lines. Six lines!

This has been staring us in the face for four years. We know the big tech platforms have created a vulnerability at the heart of our democracies. We can no longer feign ignorance. And yet we do. Perhaps at the heart of it all is the infected abscess that is the EU referendum. We need to understand what happened in it, the MPs said last week, to have any hope of protecting our elections in the future. This is an urgent matter of our national security, uncomfortably overlapping with our politics. Because what else might an inquiry find? The Russians stand accused of exploiting with disinformation and lies the same platform that Johnson’s chief aide, Dominic Cummings, exploited with disinformation and lies.

Perhaps at the heart of it all is the infected pustule that is the EU referendum

And then there’s Arron Banks. Or “page 13, footnote 50”, as Kevan Jones, the MP for North Durham, told the press conference when asked if Banks was in the report. The only individual named in the 44 pages, as a tweet from Leave.EU pointed out, “and cleared”, and who had threatened to sue the committee before it had even published.

By the time Theresa May made her speech in November 2017, I’d been working for a year on my investigation into big tech and the EU referendum and was disturbed by the lack of investigation in Britain. That week, I wrote an angry piece: “Theresa May has finally acknowledged that Britain is not insulated from fake news and lies from the Kremlin, but what is the government going to do about it?’

Nothing, it turned out. Not a thing.

Earlier this year, I spent days writing a chronology of this investigation. It’s for the court case that Mr [REDACTED] footnote 50, p13 continues against me.

November 2017 was an inflection point, not just for me but Britain too. Just three months later, Russia would use a nerve agent on our streets and kill a British citizen. “Russia, we know what you are doing,” May said. But we didn’t. We still don’t. And, under Boris Johnson, we refuse to look.

This is a vital report that demands a response. That it hasn’t got one from the man who is leading the country is a source of profound disquiet. This is a critical moment and the decisions we make now will affect our future.

If it walks like a duck and talks like a duck, it is a duck. Britain has a national security problem. And his name is Boris Johnson.

• Carole Cadwalladr is a reporter and feature writer for the Observer