“Still, donors in Saudi Arabia constitute the most significant source of funding to Sunni terrorist groups worldwide.”

This claim was advanced not by a conspiracy theorist or even an opponent of the Saudi monarchy, but by the former US Secretary of State, Hillary Clinton, in a secret memorandum circulated to American diplomats in December 2009. “Saudi Arabia”, Clinton continued, “remains a critical financial support base for al-Qa’ida, the Taliban, LeT [Pakistan-based Lashkar-e-Taiba], and other terrorist groups… which probably raise millions of dollars annually from Saudi sources.”

Conceding that “Riyadh has taken only limited action to disrupt fundraising” for such groups, Clinton was affirming the concerns long privately harboured in Washington and other Western capitals: the Saudi monarchy, recipient of massive flows of military, economic and diplomatic support from Britain and the United States, has at best ignored and at worst supported radical Sunni fundamentalist groups in the Middle East.

Given this record, the US commitment to work with Saudi Arabia in addressing Syria’s horrendous civil war is particularly confounding. There is ample evidence that the Saudis are providing material support to rebels in Syria – from crates full of Saudi weaponry found at rebel bases in Aleppo, to House of Commons enquiries seeking “to monitor any [rebel] groups that are receiving funding and arms from Saudi Arabia.” Yet “the most significant source of funding to Sunni terrorist groups worldwide” remains a valuable partner for peace in Syria. The apparent Saudi strategy of solving Syria’s conflict by increasing the flow of weapons into the country has also been enthusiastically promoted by the British government, which successfully pressured the EU into lifting an arms embargo on Syria last year.

Syria is awash with weapons, many of which have inevitably fallen in to the hands of radical groups like Jabhat-al-Nusra and the Islamic State of Iraq and Syria (ISIS – or now, the Islamic State). Whether deliberately or inadvertently, foreign interference – championed above all by Saudi Arabia and other gulf states – has exacerbated Syria’s civil war and also precipitated its spillover into Iraq. But why is the Saudi connection so consistently dismissed? Why does Britain continue to grant billions of pounds worth of arms export licences to Saudi Arabia, while remaining silent not only on human rights abuses within the Kingdom, but also on Saudi interference in Syria and Iraq?

Whether to secure oil supplies or to counter independent nationalist movements in the Middle East, Britain has played a leading role in propping up the Saudi monarchy, from its cooperation with Abdul Aziz al-Saud to unify the Kingdom in 1932, to MI6’s covert support to Saudi forces in Yemen’s brutal civil war in the 1960s, to Westminster’s military missions, beginning in the 1990s, assigned to provide “internal security training” to the Saudi Arabian National Guard at the expense of the British taxpayer.

When the United States briefly stepped back from supporting the Saudi Arabian military, Britain stepped in. The Al-Yamamah (ironically ‘the dove’ in Arabic) arms deal was concluded between Margaret Thatcher and Prince Bandar bin-Sultan in 1985, and quickly became the biggest UK arms contract in history – bringing at least 43 billion pounds in revenue for BAE Systems, the largest arms company in Britain and fourth largest in the world. Six billion pounds was allegedly distributed in bribes and corrupt commissions; up to 15 million deposited directly into Bandar’s bank account; and 60 million left aside for Prince Turki bin Nasser’s “extravagant holidays, fleets of classic cars, planeloads of shopping and blond girlfriends.”

More remarkably, as the UK’s Serious Fraud Office was investigating the alleged corruption surrounding the Al-Yamamah deal in December 2006, Tony Blair and Lord Goldsmith demanded the cessation of the investigation on national security grounds. The Saudis had warned Blair that the investigation would jeopardise diplomatic ties and counter-terrorism cooperation in the Middle East, and the Prime Minister succumbed to the blackmail.

Now, with Saudi money and weapons funnelled to jihadist anti-Assad forces, it is possible that “Saudi Arabia has created a Frankenstein’s monster over which it is rapidly losing control” – that is, the Islamic State (IS) group which has conquered large swathes of Iraq and Syria. IS, alarmingly, is now largely capable of financing itself: seizing American-made weapons and vehicles from Iraqi troops and perhaps hundreds of millions of dollars from Mosul’s central bank.

Has the Saudi regime directly supported IS, as has been alleged by Nouri al-Maliki and others? This is difficult to prove, especially since the Kingdom declared the group a terrorist organisation in March, along with Jabhat al-Nusra. Such groups also pose major potential threats to Saudi Arabia. But although Maliki’s accusations should be treated with scepticism, it is hard to ignore the long list of allegations (see, for instance, this leaked Congressional Research Office Report) detailing close links between Saudi donors, elements of the royal family and radical jihadist groups. Moreover, the Wahhabist ideology espoused by IS and others – which labels Shi’a Muslims, Yazidis, Christians and Atheists as subhumans and permits the beheading of women on charges of sorcery – has its home in Saudi Arabia and is the very basis of the Saudi state which has become such a crucial ally of Western governments.

Britain and the United States have continued to conceal these facts from the public, despite admitting them in private. As IS’s surge through Iraq may be heralding yet another phase in the West’s “War on Terror,” the Saudi connection is still routinely suppressed. As long as this hypocrisy continues, so too will the anger and chaos which fuels the spread of terrorism and radical Islam in the Middle East.