So much for “stability”, and so much for “strategic partnerships”.

The ramifications of Opec’s decision to slash production targets by another 1.2m barrels per day will be profound, though you wouldn’t know it from the “business as usual” responses from the White House and Riyadh following Sunday’s shock move.

Saudi Arabia said the cuts were a “precautionary measure aimed at supporting the stability of the oil market,” a statement instantly made to look ridiculous by the 8pc spike in global benchmark Brent crude when markets opened on Monday morning.

It was the steepest one-day increase in oil prices in more than a year, with West Texas Intermediate experiencing a jump of the same proportions to leave prices hovering around $85 a barrel.

After the sharp drop in prices following the turmoil in the banking industry, this is Saudi Arabia’s panicked attempt to install a floor to help Crown Prince Mohammed bin Salman (known as MBS) bankroll a series of mega-building projects at home that make HS2 look like it belongs on the set of Thomas the Tank Engine by comparison.

Under what has been dubbed MBS’s “Vision 2030” economic plan, the kingdom is constructing a $500bn (£400bn) futuristic “smart” city in the Arabian desert that it claims will be 33 times bigger than New York City and powered entirely by renewable energy, and a sprawling holiday resort the size of Belgium on 28,000 sq km of pristine land next to the Red Sea.

Still, the idea that ties between America and Saudi Arabia can still be called “a strategic partnership” in the face of this latest snub to Joe Biden, as national security spokesman John Kirby sought to claim, is even more preposterous, even if US officials were given a heads-up on the plan.

The worst that Kirby could bring himself to say was “We don’t think that production cuts are advisable at this moment, given market uncertainty – and we made that clear”, which threatens to be the understatement of the century. It is the second time in six months that the Saudis have delivered a massive diplomatic humiliation to the US president.

Last October’s production cut had followed months of intensive White House shuttle diplomacy as the US Government desperately sought to convince Riyadh to keep the taps open. But it was Biden’s excruciating fist-bump in a face-to-face meeting with MBS that will come to symbolise Washington’s spectacular underestimation of the shift in US-Saudi relations.

Biden saw the move as a grave betrayal and threatened “consequences”, though tellingly neglected to even give a flavour of what they might be.

But if that dealt a severe blow to an energy-for-security alliance that has endured for nearly 80 years, then this latest rebuff must represent the death knell.

In choosing to protect oil prices, MBS has sent an unequivocal message to Washington that he intends to prioritise national interests.

America's ties with the kingdom are a dirty pact that can be traced back to a meeting between Franklin Roosevelt and the Saudi founder King Abdulaziz ibn Saud in 1945 on board the American warship USS Quincy in the Suez Canal. Roosevelt wanted oil to fuel the American war effort, and its post-war recovery; in return it promised protection.

The arrangement has survived numerous major skirmishes dating back to the 1973 oil embargo. It made it through two Gulf wars, possible Saudi links to the 9/11 terrorism attacks and more recently, the murder of dissident journalist Jamal Khashoggi, which US intelligence agencies concluded was personally approved by MBS.

But it seems unlikely it will survive this, and it is no exaggeration to say that Biden’s presidency may ultimately struggle to do so as well.

The Saudis' power grab has left the octogenarian’s administration looking weaker than ever at a time when advisers are battling to contain fresh doubts about his health sparked by a decision to miss the King’s Coronation next month.

On the economic front, a fresh supply squeeze risks a new inflationary spiral that will be felt acutely. In a country where pump prices have long been capable of determining who holds office, the political fallout will be inescapable.

Goldman Sachs is predicting oil prices of $95 a barrel by the end of the year, and $100 a barrel by December 2024 - a disaster for a president who has repeatedly staked his presidency on gas prices being suppressed. In February, Biden promised to “work like the devil” to address high prices, a pledge at odds with an admission that he also had little understanding of what the cause was.

The damage to America’s standing on the world stage threatens to be equally catastrophic. If Biden’s critics wanted a clear sign of Washington’s waning global influence then they need look no further than Saudi Arabia’s defiance in the face of his threats.

The Saudi view of the world, and its values, has always sat more comfortably with other autocracies than Western democracies but the breakdown in relations with the US threatens to unleash a geopolitical earthquake.

As America surrenders control of the Gulf, a new Saudi-Russia-China axis is emerging that makes it harder to enforce US-led sanctions against Moscow, and for the White House to counter the rising power of an increasingly anti-Western Beijing.

Under Biden’s increasingly inward-looking administration, the US has seldom looked so weak.