The tenth anniversary of the 2001 terrorist attacks on New York and Washington will be accompanied by the usual solemn political pronouncements and predictable media retrospectives. Pundits will point out that the West’s own economic mismanagement of the past decade has done more to weaken Europe and North America than the Islamists’ attacks. Some others will note how radical Islamists are still strong in Afghanistan and point to the recent downing of a military helicopter with dozens of US troops dead. Still others will use the anniversary to pontificate on how our concerns about Islamism have given racists an excuse to tarnish an entire religion. We will also hear about how the democratic uprisings in the Arab world—Libya being the latest—have undermined Islamists (by providing the region’s disgruntled masses with examples of positive, instead of destructive change).

All of these points are well and good and worth hearing again. But they shouldn’t distract us from a very precise and practical problem that hasn’t been addressed: the refusal of the CIA to disclose the details of its involvement with Islamist groups. In recent weeks, the agency has tried to block sections of a new book that deals with its handling of al-Qaeda before and after September 11. But this is only one part of a large-scale cover-up that Western governments have been perpetrating about decades of ties to Islamist organizations. Until we clarify our murky history with radical Islam, we won’t be able to understand the background of the September 11 attacks and whether our strategies today to engage the Muslim world are likely to succeed.

Of course some of this history is well known. The blowback story—how the US armed the mujahedeen, some of whom morphed into al-Qaeda—has been told in book and film. We are also getting a sense now of how parts of the US-backed Pakistani military-intelligence complex have actively supported radical Islamists. Collusion between Britain and Islamist movements over the past century has also been explored. And of course, Israel’s support for Hamas as a counterweight to the Palestinian Liberation Organization has gone down as one of the great diplomatic miscalculations of recent history.

But compared to the full scope of the issue, these insights are meager. To date, the Central Intelligence Agency continues to block access to its archives relating to radical Islam or cooperation with Islamist groups like the Muslim Brotherhood. In the course of researching my book on the Brotherhood’s expansion into the West, I applied numerous times under the Freedom of Information Act to see documents concerning events in the 1950s, some of which had been confirmed by already declassified State Department cables. Inevitably the CIA responded with the blanket exception of “national security” to justify denying access to any files.

Despite the CIA’s information blockade, it is clear from interviews with CIA operatives and other countries’ intelligence archives that the CIA was courting groups like the Brotherhood as allies in the US’s global battle against communism. In Egypt, the charge was often made by the government of Gamel Abdel Nasser that the Muslim Brotherhood was in the CIA’s pay. This was also a view of some Western intelligence agencies, which flatly declared that Said Ramadan, the Swiss-based son-in-law of the group’s founder, was a US agent. The agency may have—but for this we need access to its archives—colluded with Ramadan in attempting a coup against Nasser.

The CIA certainly did help the Brotherhood establish itself in Europe, helping to create the milieu that led to the September 11 attacks. The mosque in Munich that Ramadan helped found, for example, became a hotbed of anti-US activity. The man convicted as a key perpetrator of the 1993 attack against the World Trade Center had sought spiritual counseling at the mosque before leaving to carry out his attacks. And in 1998, the man believed to be al-Qaeda’s chief financial officer was arrested near the mosque and also sought spiritual counseling from the mosque’s imam. An investigation based on this arrest traced radical Islamists right to a second mosque—the al-Quds mosque in Hamburg—where three of the four 9/11 pilots worshipped, it but failed to make the final link. This isn’t to say that the CIA was behind the September 11 attacks but that US collusion with Islamists in the Cold War bore bitter fruit in later years—making it imperative that we understand exactly what happened in those seemingly distant years of the 50s, 60s and 70s of the last century.

More recently, despite Washington’s sometimes hostile public rhetoric toward to the Brotherhood, it is clear that the administrations of George W. Bush and Barack Obama have tried to court the movement. Internal CIA analyses from 2006 and 2008, which I obtained, show that the Brotherhood was viewed as a positive force and potential ally—this time not against communism but Islamist terrorism: the Brotherhood was considered a moderate Islamist group and thus able to channel grievances away from violence toward the United States (even if Brotherhood theoreticians did not renounce violence against Israel or US soldiers). The State Department also used US Muslims close to the Brotherhood to reach out to Islamists in Europe. Such support has given these groups legitimacy in the United States and Europe.

The CIA is blocking the release of information because the subject remains sensitive—both for the West and the Muslim world. In Washington, the CIA could come under fire if its own archives would confirm and fill out the current sketch view of history. For the Brotherhood, amid its current re-emergence as a major political force in Egypt and other countries, it would be extremely damaging to know that illustrious figures in its history were working for the country that most exemplifies the decadent, imperialist forces it has struggled against for decades.

Revealing this history could be painful but necessary to strip away the doublespeak that both sides have used to describe their dealings with each other. This isn’t to say that releasing information should be used to bash cooperation with Islamists. Clearly the United States and other Western countries need to deal with groups like the Brotherhood, and perhaps in some situations even to support them: for example if the Brotherhood really were to come to power democratically in Egypt, the United States would be obliged to deal with such a government. For the Brotherhood a case could be made that in past decades, when its members were so badly repressed by authorities in the Middle East, that some sort of help from the West was necessary to avoid destruction by the authoritarian governments that persecute it.

These are legitimate arguments. But they can only be made if the full history of these relationships is made known rather than kept hidden. To do this will require action from Congress. The CIA did not release documents concerning US intelligence dealings with Nazi officials, for example, until it was forced to by the passage of the Nazi War Crimes Disclosure Act of 1998. This piece of legislation compelled US government agencies to release all files on their dealings with the Nazis during and after the war. It lead to an incredible flood of information on the topic, helping us understand, for example, US collaboration with ex-Nazis after the war.

We need a similar law today. This is not to draw a parallel between Islamism and Nazism—an argument that is tendentious and counter-productive. The only parallel is that the US government has dealt with these questionable organizations and is so unwilling to admit this that it will take specific instructions from Congress to make these dealings public. Whatever the merits of these policies they are based on a long-standing, but still mostly secret, strategy. As Western governments seek to distinguish between “good” and “bad” Taliban in Afghanistan and Pakistan, or between the Muslim Brotherhood and more radical groups in the Middle East, understanding this strategy—and its efficacy—has never been more urgent.