The massive leak of cables is in part an unintended consequence of a decision to step up data-sharing between government agencies to prevent a repeat of the September 2001 terrorist attacks.
It emerged from post mortems on 9/11 that information that might have thwarted the attacks did not reach the
right people because of barriers between departments and bureaucratic turf wars, not least between the FBI and the CIA.
So the Bush Administration ordered a wider pooling of information and a sweeping reorganisation of the country's fragmented intelligence and security community.
The overhaul included a huge increase, to between 500,000 and 600,000, in the number of people with access to SIPRNet - the Secret internet Protocol Network - used by the Pentagon to transmit classified information.
Among SIPRnet's more recent users is the State Department, which, according to the Washington Post, wanted to avoid the expense of setting up a network of its own for diplomatic traffic.
Inevitably, however, broader access increased the risk of leaks - either by accident, or deliberately by someone with a grudge against the system. The latter appears to have happened if, as has been alleged, WikiLeaks' source turns out to be Bradley Manning, a 23-year-old Army intelligence analyst who was based in Iraq.
Though only a private, Manning had access to SIPRNet and thus to the 250,000-plus cables to and from US diplomatic missions.
The challenge for the authorities is to make the system more secure, but without re-erecting old barriers.
In an initial move, the Pentagon announced it had removed a feature from its system that allowed data to be transferred to removable devices. In future two people must be involved in any transfer from secret to non-secret networks. Vetting of personnel is also likely to be stepped up.
But extra precautions rarely have the desired effect. Blockbuster leaks, from the 1971 publication of the Pentagon Papers to the post 9/11 disclosure the Government was engaged in unauthorised eavesdropping, predate the furore over WikiLeaks.
MORE TO COME
*251,288
cables to be released
*8017
from the office of the Secretary of State
*15,600
are classified* as secret
*WikiLeaks says most are unclassified.
-Independent
