In White House parlance it’s known as the ‘PDB’. By any standards the 'president’s daily brief' on intelligence matters is among the most tightly controlled daily documents in the world.

According to former intelligence analyst, David Priess who was a briefer in the Bush administration, the PDB document is “very short, very punchy, small enough that it could be folded and put into the president’s suit pocket.”

Over many decades US presidents have considered the PDB as a critical start to their day.

President Bill Clinton preferred to read his daily intelligence briefing in paper form. George W. Bush insisted on a daily in-person briefing. President Obama consumes his digitally, on a custom tablet.

“It gets them thinking about what’s going to happen that day, that month or that year,” says US intelligence veteran Barry Pavel, who has served the past two administrations.

Right now Donald Trump takes a slightly different approach to the PDB.

By his own admission, the president-elect sees it as a case of, “I get it when I need it.”

Justifying this is easy for Trump who when asked about the PDB gave a characteristic response. “I'm, like, a smart person. I don’t have to be told the same thing in the same words every single day for the next eight years.”

Trump’s apparent indifference towards the importance of the PDB, is just one indication of what many see as his wider disdain for the US intelligence community.

With less than two weeks until Trump is sworn in as the 45th President of the United States, few issues loom as large as the real estate mogul’s ongoing battle with US intelligence over its assertions that Russian hackers interfered with the US election.

For many US political observers it appears as if Trump is already engaged in a battle of wills with his own spies, something they feel does not augur well for both parties and will only serve the interests of foreign adversaries.

Time and again during his presidential campaign Trump questioned the competence of and quality of US intelligence gathering operations, and since then relations have only deteriorated.

That this standoff is being played out on social media, notably Twitter by Trump himself, only adds to the unprecedented nature of such a face off between a president-elect and the intelligence community.

Even by Trump’s usual standards, his recent Twitter posts on the subject have been little short of outrageous.

About to be briefed on an investigation into the alleged Russian hacking of Democratic Party emails, Trump posted this tweet on Tuesday evening: “The ‘Intelligence’ briefing on so-called ‘Russian hacking’ was delayed until Friday, perhaps more time needed to build a case. Very strange.”

Not to be outdone NBC television news and other media outlets appeared to have got hints of what intelligence leaders would tell Trump before his briefing last Friday. This prompted one observer on Twitter to make the wry comment: “I salute the genius at CIA who realised they could get Donald Trump to pay attention to intel briefings by putting them on NBC news.”

All joking aside, president-elect Trump and his team are now coming into office with an adversarial relationship toward the US intelligence community of the kind not seen since Jimmy Carter’s administration in the post-Watergate era.

The key question within US political circles now, is just how serious is Trump’s spat with his spies, and what are the long-term implications of this acrimony for both parties?

Before addressing these questions though, it’s worth remembering that over the last few days, US intelligence agencies have unequivocally concluded that Russian President Vladimir Putin ordered an effort to help Trump’s electoral chances by discrediting Democrat Hillary Clinton in the recent presidential campaign.

“We assess Russian President Vladimir Putin ordered an influence campaign in 2016 aimed at the US presidential election,” the intelligence report said. “We further assess Putin and the Russian Government developed a clear preference for President-elect Trump. We have high confidence in these judgments.”

The report said Russian military intelligence, the GRU, used intermediaries such as WikiLeaks, DCLeaks.com and the "Guccifer 2.0 persona" to release emails that it had acquired from the Democratic National Committee (DNC) and top Democrats as part of the effort.

While omitting classified details, the report was the US government's starkest public description of what it says was an unprecedented Russian campaign to manipulate the American body politic.

Trump’s reaction has sent much of the US political establishment into a spin. Some say a far more plausible explanation for Trump’s response is that he continues to view the question of Russian meddling through the prism of his own fragile ego.

As Trump sees it, if it’s established that the Russians meddled in the election to harm his opponent, some Americans will be confirmed in the view that Trump’s election was illegitimate.

So what then will be the consequences of the whole 'Trump versus US spies' farrago? Certainly to begin with on an open political level, it will give ammunition to Democrats and Trump's fellow Republicans in Congress who want tougher action against Russia, setting the scene for a potential showdown with Trump. It could also give a boost to members of Congress seeking an independent, bipartisan investigation of Russian hacking.

These moves would be very much within the public political arena. But what of those more embedded tensions between Trump and the US intelligence community?

There is little doubt that Trump’s latest attacks have infuriated intelligence officials past and present from across the political spectrum. Among them are the director of national intelligence, James R. Clapper Jr., and former CIA director James Woolsey who has now quit Trump’s transition team in protest.

Intelligence officials are unhappy too that Trump - again on Twitter – has sided with WikiLeaks founder Julian Assange’s statements about not receiving emails stolen from the DNC, rather than the findings of US intelligence agencies.

Trump has adopted this view even though Assange himself has disavowed his ability to ascertain the ultimate source of material he leaks, making the president-elect’s reference almost meaningless.

“With every conspiracy theory-laden tweet and erratic off-the-cuff comment, the president-elect does damage to our national security, while raising new concerns about his capacity to grow into the job,” observed Rep. Adam Schiff of Burbank, the ranking Democrat on the House Intelligence Committee.

“When he belittles the reputation of the brave and hard-working professionals in the intelligence community, he impairs our national security and the prospects for the success of his own administration.”

And there perhaps in Schiff’s remarks lies the real problem for Trump. As history has shown, all to often it does not bode well for a US president to rail so openly against the intelligence establishment.

Richard Nixon famously disliked the CIA and was sceptical of its analysis. Nixon once told his Director of CIA James Schlesinger: “Get rid of the clowns. What use are they? They’ve got 40,000 people over there reading newspapers.” Within three months, Schlesinger pushed out 10 per cent of the workforce. Nixon of course faired little better in the long run. Invariably, the CIA survives to fight another day.

In the late 1970s, after a series of Congressional committees raised fears of the CIA having got out of control, President Jimmy Carter brought in a new director, Stansfield Turner, who cleared out the agency of many of its staff leading to further acrimony.

Then there was CIA Director James Woolsey whose relationship with Bill Clinton was so non-existent that when a small aircraft crashed on the White House lawn, the joke was that it was Woolsey trying to get a meeting with the president.

Certain intelligence observers do not rule out the possibility of some within the security agencies ranks who might try to take matters into their own hands.

“There may be some who could try to undermine Trump by leaking embarrassing documents and committing criminal acts in the process,” says Aki Peritz a former CIA analyst.

“Certainly in an industry where millions of people hold security clearances, there will be some who could try unilaterally to take action to effect change or cause disruption,” Peritz points out.

Treating the intelligence agencies as a whipping boy for policy makers’ mistakes, is pretty much par for the course say former employees like Peritz.

Some cite the old Washington expression that “in this town there are only two possibilities: policy success and intelligence failure.”

Despite these accepted notions the current US intelligence community has other reasons to be concerned.

Last week The Wall Street Journal reported that the incoming Trump administration is working on plans to “restructure and pare back” the Office of the Director of National Intelligence and the CIA, “cutting back on staffing at its Virginia headquarters and pushing more people out into field posts around the world.”

Trump spokesman Sean Spicer denied such reports. But as Max Boot, a senior fellow for national security studies at the Council on Foreign Relations pointed out, Spicer’s “record for veracity is not exactly unimpeachable.”

Boot also argues though that should Trump be hell-bent on restructuring these agencies then this it not necessarily an altogether bad thing.

“There is little doubt that the US intelligence community is top-heavy and over-bureaucratised. There are too many paper pushers in Washington and too few effective case officers in the field,” says Boot.

“To borrow British archetypes, we have a deficit of James Bonds and a surplus of Sir Humphrey Applebys; we could use more of the former and fewer of the latter.”

Trump’s proposed restructuring plans would come in the wake of an already extensive remodeling of the CIA through a massive and controversial restructuring under present Director John Brennan.

Those changes themselves have been described as “the most far-reaching organisational shake up since the CIA’s creation in 1947.”

Among the many shifts was a moving of the traditional power centre of the CIA, away from separate operational, analytical and technical components focusing largely on strategic intelligence, to 10 more tactically oriented mission centres focusing on regional and transnational issues.

“The most radical part of this shift from the CIA’s perspective," says Max Boot, writing in an analysis piece for Foreign Policy magazine, is that these “mission centres fuse together operations officers, analysts, technical intelligence officers and others,” thus piercing the traditional wall between analysts and operators.

In other words, the CIA right now is still reeling from major changes even before Donald Trump sets foot in the White House. Some intelligence observers say that yet more turmoil especially any created by Trump’s incoming administration and likely tinged with bad feeling will not go down well at CIA headquarters in Langley and elsewhere.

According to Max Boot, there is a good chance that any restructuring Trump implements will be seen, rightly or wrongly, not as a way to optimise the agencies’ performance but rather as payback for what he sees as a personal affront.

“There is a real risk that after January 20 the intelligence community will experience a crisis of confidence the likes of which we have not seen since the witch hunts of the 1970s led by the Church and Pike Committees in Congress,” warns Boot.

Some point to how Trump has already had a go at the CIA and other agencies over their flawed intelligence gathering on Iraq. This mood they worry might prevail with Trump in the White House eroding public confidence in agencies like the CIA and FBI.

“Bringing back the Saddam stuff is painful, it’s ripping open a scab that’s largely healed,” says Andrew Liepman, a former senior CIA official who also worked providing PDBs under several administrations.

“The confidence that the country had that the intelligence community is reliable and objective really took a hit, after the lead-up to the Iraq War, when intelligence agencies mistakenly advised George W. Bush that the Iraqi dictator had weapons of mass destruction.

“For 15 years, (intelligence agencies have) been trying to climb out of the hole. I hope they don’t get pushed back into that hole,” Liepman says.

In all of this ongoing bitterness between Trump and his spies, it is interesting that incoming CIA Director - another Republic Congressman, Mike Pompeo – has made very little public comment.

On the whole, those close to the CIA have suggested officials there are less worried by his nomination than that of other Trump appointed officials like incoming National Security Advisor Michael Flynn.

He is reported to have a degree of animosity towards the CIA and the Directorate of National Intelligence - which plays an over-arching role - after his stint running the Defence Intelligence Agency.

For the time being the bad blood continues to flow. The US intelligence community is far from infallible and it is only right that any president and their administration have responsibility to subject its conclusions to scrutiny.

President-elect Donald Trump however, with his habit of making policy through dead-of-night tweets, presents something of a new challenge for US intelligence.

As a Los Angeles Times editorial soberly pointed out last week: ‘Trump is undermining confidence in the intelligence community with each fight he picks and someday, in a true national security crisis, he will find that the American people no longer believe them.’

With Trump’s inauguration less than two weeks away, that day and that crisis might not be so far off.