Donald Trump has been on Twitter again this morning, this time in reaction to an admonishment made on Sunday by outgoing CIA director John Brennan criticising the president-elect for comparing the US intelligence community with Nazi Germany and urging him to rein in “talking and tweeting” that could impact on national security. Trump responded by slamming the credibility of US intelligence on key national security issues and attacking Brennan personally. “Was this the leaker of Fake News?” Trump tweeted.

This spat is the latest in a series of hostile exchanges that reflect ever-worsening discord between the US president-elect and the American intelligence institutions. The implications are potentially severe, not only for the day-to-day operations of the US intelligence agencies but also for the very prospect of rational government, which relies on a functioning relationship between those whose job it is to understand the world and those who make decisions.

.@FoxNews "Outgoing CIA Chief, John Brennan, blasts Pres-Elect Trump on Russia threat. Does not fully understand." Oh really, couldn't do... — Donald J. Trump (@realDonaldTrump) January 16, 2017

It’s safe to say that the US intelligence community’s handling of the Trump dossier did nothing to improve its relationship with the incoming commander-in-chief. The two-page summary of unverified reports suggesting “kompromat” on Trump, which landed on the desks of the president and president-elect, handed Trump and his team the opportunity to accuse them of being complicit in the spread of “fake news” and “phoney stuff”.

While these accusations are unfounded and over the top – the Trump dossier has nothing to do with the separate problem of fake news – the situation does highlight the critical need for intelligence professionals to adhere to the tradecraft standards that command the trust that decision-makers must place in them. The tradecraft that matters most these days for intelligence organisations (contrary to fake news peddlers) relates to the analysis and assessment of information, rather than its collection. In an age of information abundance, collecting information is arguably less challenging than the task of extracting value from it for decision-making purposes. Indeed, information becomes intelligence only after it has been analysed and assessed, and decision-makers require intelligent judgments.

While the professionalisation of intelligence in government circles has led to the development of cutting-edge analytical and assessment techniques, the corporate intelligence world tends to be less sophisticated, where the line between “intelligence” and “information” is more blurred. The privately produced source reports about Trump do not constitute intelligence product; they simply present information that might or might not be true. It remains surprising, therefore, that a two-page summary of this reporting, which fell well short of normal tradecraft standards, was included in high-level government briefings.

The fallout of the Trump dossier handling will present unprecedented challenges to US intelligence organisations, activities and knowledge. As former CIA acting director Mike Morell warned on CBS’s Face the Nation on 8 January, staff morale will undoubtedly suffer if President Trump turns out to be permanently uninterested in what they do. It is unlikely that he will seek to actively invest in the intelligence community or empower its leadership; there is already loose talk suggesting the administration aims to weaken the influence of the office of the director of national intelligence, who is supposed to serve as the principal adviser to the president on such matters, following the perceived mishandling of Russian hacking claims.

Intelligence agencies should never have allowed this fake news to "leak" into the public. One last shot at me.Are we living in Nazi Germany? — Donald J. Trump (@realDonaldTrump) January 11, 2017

Even if Trump doesn’t restructure US intelligence organisations in any meaningful way, it remains highly doubtful that he will ever become a keen consumer of intelligence material. As per Morell’s warning, the existence of a commander-in-chief that doesn’t appear to value intelligence product or process could jeopardise the US’s ability to recruit sources, especially those motivated by a strong sense of patriotism and the desire to make a difference. A disengaged president would surely do little to incentivise agents to take risks to provide information if there is little prospect of that information ever influencing the thinking of high-level decision-makers serving in a Trump administration.

Perhaps most concerning, however, are questions surrounding the status and handling of intelligence as a type of knowledge, especially as it pertains to national security, foreign affairs and defence. “I know more about Islamic State than the generals do” is a statement typical of Trump, but the emergence of a thick “post-truth” atmosphere seeping through American (and British) political and media institutions risks stifling expert opinion where it is needed most.

In 1949, the great American academic and serviceman Sherman Kent introduced the concept of “strategic intelligence”. The core idea was that intelligence played a critical role in supporting rational government, by helping policymakers gain a “big picture” understanding of the world around them and make informed strategic decisions. It became the backbone of the western intelligence model, which serves as the blueprint for the US and other democratic countries worldwide.

Its fundamental purpose is to “provide truth to power”, promote evidence-based thinking, and present perspectives that might challenge the preconceptions of those in charge. It stands in stark contrast to politicised models, often found in totalitarian states, that feature organisations that struggle to resist the pressure to simply say what their political masters want to hear. History shows us that the relationship between intelligence and policy has rarely been straightforward, but it will struggle to provide any examples of previous US presidents-elect publicly denigrating the very institutions that US policymakers rely on for objective insight and evidence-based perspectives that might serve to challenge the ideological convictions of politicians.

The western intelligence model has survived in the US for almost 70 years. It may now be facing its sternest test yet.