" McNamara’s electronic fence, which the Jasons called an “anti-infiltration barrier,” was constructed along the Ho Chi Minh Trail, at a cost of $1.8 billion, roughly $12 billion in 2015. It had very little effect on the outcome of the Vietnam War and did not help the United States achieve its aim of cutting off enemy supplies. "

― Annie Jacobsen , The Pentagon's Brain: An Uncensored History of DARPA, America's Top-Secret Military Research Agency