The whistleblower website Wikileaks has sent more than 250,000 US diplomatic cables, some dating back 40 years, to five international newspapers. But what is the scope and significance of this mountain of “top secret” information?

How many documents were leaked?

The leak consists of 251,287 US diplomatic cables and documents sent by more than 250 embassies and consulates around the world. They can be divided into six categories: secrets not to be shared with non-Americans, secrets, confidential information not to be shared with non-Americans, confidential information, and unclassified information for official use and unclassified information. The information dump does not contain "top secret" cables.

What is the importance of this leak?

The United States has harshly condemned the publication of the documents. It has called the leak “harmful” to its national security, and said it puts “lives” and “national interest” at risk. State department officials have insisted that the leak endangers the lives of US diplomats, members of the intelligence community and foreign allies of the US. Because of the absence of "top secret" cables, the potentially most controversial aspects of US diplomacy do not appear in the revelations. Nevertheless, in the French digital journalism website owni.fr, Jean-Dominique Merchet, an international defence expert, says: "The diplomats of the world will now be reluctant to share information with the [USA], fearing to see it on the Internet six months later. One thing is certain. Wikileaks has weakened the United States politically."

What is the time period covered by the cables?

The oldest cable comes from Argentina in 1966, the year that Juan Carlos Ongania rose to power after a military coup d’état. But 90 percent of documents were sent between 2004 and 2010 and 50,000 cables are from President Barack Obama's tenure.

Where did the documents come from?

All of the cables came from SPIRNet (Secret Internet Protocol Router Network), the main computer network used by the US Department of Defense to transmit classified documents. Only the files given the "top secret" classification are not sent via SPIRNet and are transmitted on another more restricted network. Some 2.5 million US government staff and officials have access to SPIRNet.

Why aren't all of the cables available for download?

For the first time in its short history, WikiLeaks has decided not to directly publish all of the leaked documents on its website at once, opting to disclose the first batch of cables to five international newspapers Le Monde (France), El Pais (Spain), Der Spiegel (Allemangne), The New York Times (United States) and The Guardian (United Kingdom).

The leaked cables will be disclosed to the public as they are processed, researched and analysed by the newspapers' editorial teams. Some documents will be censured to protect the identity of people who might be endangered by the revelations.

Which countries are most concerned about these leaks?

Most cables come from Washington (8,017). The second largest source is the US diplomatic mission in the Turkish capital of Ankara (7,918). Then there is Baghdad (6,677) and Tokyo (5,697). In Western Europe, most cables come from Paris (3,775). The number of documents sent from China may seem low (3,297), given the troubled relations between the Asian superpower and the United States.

What are the topics covered by the cables?

The two most important topics are political relationships with foreign governments (145,451 papers) and internal government affairs (122,896). Human rights ranks third (55,211) and “economic conditions” in other countries (49,044) fourth.

Who is behind these leaks?

The source of these cables remains anonymous, but Bradley Manning, a US soldier and army intelligence analyst, has become a key suspect among the traditional and non-traditional media. The 23-year-old private was detained by US authorities in May and has been charged with “transferring classified data onto his personal computer and adding unauthorised software to a classified computer system” as well as “communicating, transmitting and delivering national defence information to an unauthorised source”.