For nearly 20 minutes last April, China Telecom Corp., the nation’s largest fixed-line phone carrier, hijacked  15 percent of the world’s internet traffic routes. The traffic, which was re-routed through servers in China, included data from the U.S. government and military networks, including data from the Army, Navy, Air Force, Marine Corps, the Office of the Secretary of Defense, the Department of Commerce, NASA, and the U.S. Senate. Traffic from civilian business sites was also diverted, including traffic from Microsoft, Dell, and Yahoo.

China denies that it diverted the internet traffic on purpose, or that it did anything with the data, but a report submitted to Congress on Wednesday by the U.S.-China Economic and Security Review Commission said China’s motives and actions on the data are unclear.  According to the Commission, the unprecedented type of access China had to this data could potentially give them the ability to perform digital surveillance, disrupt digital transactions, prevent users from access their intended sites, or divert traffic to spoof sites.

National Defense experts say the hijacking has gone largely under-reported by media because the causes and potential consequences are too technical for the the majority of the public to grasp.

Dmitri Alperovitch, vice president of threat research at McAfee said: “This is one of the biggest — if not the biggest hijacks — we have ever seen.” And it could happen again, anywhere and anytime. It’s just the way the Internet works, he explained. “What happened to the traffic while it was in China? No one knows.” The data could have been kept an analyzed, he said.

Alperovitch explains that because the large telecommunications networks across the globe operate on a system of mutual trust. Machine to machine interfaces send signals to the internet that let other service providers know they have fast and efficient routes open on which data packets can travel. When this happens, data is often routed that way.

Alpervitch says traffic rerouting like this happens accidentally a few times a year, but when this happens, often the traffic reaches a dead end and there is a disruption in service. What sets this incident apart from others, Alpervitch says, is the sheer magnitude of traffic that was rerouted to China and then sent back out again without any disruption problems. “Imagine the capability and capacity that is built into their networks,” he said. “I’m not sure there was anyone else in the world who could have taken on that much traffic without breaking a sweat.”