The US government has been installing "back door" surveillance functionality into US-made internet devices.
The claim is the latest to emerge from journalist Glenn Greenwald, using documents leaked by former National Security Agency (NSA) contractor Edward Snowden.
According to Greenwald, who is writing a book about the NSA and the "surveillance state", an NSA report from June 2010 indicates that the "NSA receives - or intercepts - routers, servers and other computer network devices being exported from the US before they are delivered to international customers".
Written by the head of the NSA's Access and Target Development department, the report goes on to reveal how the agency implants back door surveillance tools into the hardware, repackages them - including the factory seal - and sends them on. "The NSA thus gains access to entire networks and all their users," says Greenwald, quoting the document: "SIGINT [signals intelligence] trade craft... is very hands-on (literally!)".
The NSA calls this "supply chain interdiction". It brings into question the integrity of networking products produced by Cisco Systems, Juniper Networks and Redback, all of which are used in internet backbones. It also raises question marks over logistics and delivery companies transporting such goods.
The report continues: "In one recent case, after several months a beacon implanted through supply-chain interdiction called back to the NSA covert infrastructure. This call back provided us access to further exploit the device and survey the network."
Greenwald compares the NSA programme with US politicians' warnings that the shift of manufacturing to China meant that computer equipment could be compromised by Chinese intelligence agency bugs.
"It is quite possible that Chinese firms are implanting surveillance mechanisms in their network devices. But the US is certainly doing the same," concludes Greenwald.