The Observer view on the need to know the extent of the Russian threat to Britain

The formal “finding” by US intelligence officials that the same covert Russian military action unit responsible for the Salisbury nerve agent poisonings has paid Islamist militants to target and kill British troops in Afghanistan is deeply shocking. Boris Johnson’s government now faces a renewed diplomatic confrontation with Vladimir Putin’s regime in Moscow from which it must not shy away.

According to an official US briefing shared with Britain last week, agents attached to Unit 29155, an arm of Russia’s GRU military intelligence agency, offered bounties to Taliban-linked extremists in return for killing American and British troops. The US intelligence agencies’ finding was first reported by the New York Times.

The British and US governments concluded last year that Unit 29155 operatives were responsible for the March 2018 attack in Salisbury on Sergei Skripal, a former GRU officer who had defected to Britain, and his daughter. Although Putin denied any involvement, the evidence was conclusive. The incident prompted western sanctions against Russia.

Britain and the US are not the only countries to have suffered from apparently systematic attempts by Russia’s president and his shadowy assassins and spooks to destabilise the west. Russian methods include fake news social media campaigns, cyber-attacks, sabotage, subversion, deniable military operations and covert killing.

One such outrage occurred in Berlin last year, when an anti-Moscow Chechen separatist was murdered in what German prosecutors termed a state-sanctioned assassination. Unit 29155 has also been linked to an attempted coup in Montenegro, the poisoning of a Bulgarian arms manufacturer and subversion in Moldova.

Of key concern are well-documented clandestine GRU efforts to meddle in foreign elections, notably in the US in 2016. Robert Mueller, who investigated claims that Republicans colluded with Moscow to defeat Hillary Clinton, found that Donald Trump’s campaign was aware of Russian interference and hoped to benefit from it electorally.

That alleged connection may help explain why Trump’s White House, which was first told of the Russian bounty-hunting operation in Afghanistan in March, has so far taken no action. By keeping silent, Trump may hope to salvage his proposed “peace deal” with the Taliban. He may also be wary of upsetting Putin. Trump previously opposed sanctions imposed on Russia over US election meddling.

Related: Johnson and May ignored claims Russia had 'likely hold' over Trump, ex-spy alleges

According to reports of in-camera testimony to MPs in 2018, Christoper Steele, a former MI6 spy, claimed the Russians had a “likely hold” on Trump and may also have covertly funded the pro-Brexit referendum campaign in 2016. Steele’s testimony formed part of an inquiry by parliament’s intelligence and security committee (ISC) into Russian interference in Britain.

It is an absolute scandal that the ISC’s report, which was completed in October, has not yet been published. Johnson refused to release it before last December’s election, for largely unexplained reasons, and it is still not in the public domain. Opposition MPs now suspect a cover-up. Are they right?

Suspicions that Steele is correct in suggesting that Johnson, as foreign secretary, and Theresa May, the then prime minister, did not act on his ISC evidence because they feared upsetting Trump must be fully examined and, if baseless, laid to rest.

Likewise, claims that Moscow tried to influence the outcome of the Brexit referendum, and that Russian oligarchs have funded the Conservative party, are extremely damaging to British democracy and must be exposed to unfettered public scrutiny and debate. Otherwise, people will ask, what has Johnson got to hide?

Publication of the ISC report is rendered more urgent by the revelations concerning the bounty-hunting of British servicemen and women. There are about 1,100 British military personnel in Afghanistan. If this country’s soldiers, politics, democratic votes and way of life are under sustained attack from Putin’s Russia, the public has the right to know – and the right to expect a vigorous response from Johnson as a matter of the utmost urgency.