Top-secret unit of young hackers spearheads America's programme to infiltrate communications worldwide.
They are mostly young, casually dressed and fearsomely computer literate - and, if they sound just like typical Silicon Valley start-up geeks, they are.
But the staff of the National Security Agency's Office of Tailored Access Operations, or TAO, are among the most powerful weapons in the United States' formidable cyber-arsenal.
The top-secret unit, whose existence is rarely acknowledged, hacks computers around the world, harvesting data, monitoring communications and even mounting cyber-attacks.
In a new report based on internal NSA documents, the German weekly Der Spiegel describes TAO as "something like a squad of plumbers that can be called in when normal access to a target is blocked".
TAO workers are said to be "considerably younger" than most NSA employees and many have been recruited at hacker conferences.
TAO was established in 1997 to hack into global communications at a time when less than 2 per cent of the world's population had access to the internet. Today, it has offices in Hawaii, Georgia, Texas, Colorado and at NSA headquarters at Fort Meade, Maryland, where there are estimated to be 600 TAO operatives.
The documents obtained by Der Spiegel suggest that during the mid-2000s, TAO accessed 258 targets in 89 countries. By 2010, it conducted 279 operations a year worldwide. These included hacking the private, protected networks of world leaders, including rivals and allies of the US. Among their targets was Mexico's Secretariat of Public Security, described as a "goldmine" of information on shared US-Mexican concerns such as drug and human trafficking.
In 2005, TAO is thought to have gained access to a vast trove of information about China's cyber-intelligence activities. According to a recent Washington Post report, the unit was also instrumental in the hunt for Osama bin Laden, gathering intelligence from mobile phones used by his al-Qaeda colleagues.
Much of TAO's work focuses on mass telecommunications and it relies on the secret co-operation of the three largest US telecoms companies - AT&T, Verizon and Sprint - as well as major US internet service providers.
It has also hacked European networks and, after one "sustained TAO operation", managed to access BlackBerry's famously secure BES email servers. Another top-secret document outlines the agency's infiltration of "SEA-ME-WE-4", a vast underwater cable telecoms network that links Europe to the Gulf states, Pakistan, India and the Far East.
The unit has even been known to organise the interception of shipping deliveries to its targets, installing its own "back doors" in hardware made by Microsoft, Huawei and others, providing covert, remote access to the devices once they are in use.
The current budget plan for US intelligence estimates that by the end of 2013, some 85,000 computers worldwide would have been infiltrated by the NSA. This year a former agency official told Bloomberg Businessweek TAO now gathers two petabytes, or two million gigabytes, an hour of data from overseas computer networks.
And yet, the former head of TAO claimed in one document that "it is not about the quantity produced but the quality of intelligence that is important". The unit had produced "some of the most significant intelligence our country has ever seen".