Fortunately, I know one of the people who helped develop the ARPANET, Professor Peter Kirstein. For more than a decade, starting in 1973, Kirstein ran the UK’s connection to ARPANET out of his office at University College, London (where he remains a professor of computer communications). So I phoned him, and he told me:

„Unless everyone’s been lying to me for 40 years, the ARPANET was not intended as, or used as, a surveillance system. The 1966 concept could never include more than 64 locations, with four computers in each location. It took the invention of the Internet Protocols a decade later to envisage a capacity of millions of locations and billions of devices.“