An alarming article in the New Yorker on 6 August said that an engineering professor has proved — and exploited — its vulnerabilities. This came after the US Department of Homeland Security asked him to test jamming of the technology in action. However, he said that he wanted to focus on a different, more sophisticated threat – spoofing the GPS signal, not just interfering with it but actually replacing it with a phantom GPS signal. The article looks at the history of GPS, which dates back to the early 70s, and its deficiencies and problems – as well as how it can be intercepted, interrupted and spoofed. Such things need not be high-tech, the article giving the example of many truck drivers on the New Jersey Turnpike using jammers to thwart their bosses’ tracking programmes, with interference eventually disrupting the GPS-based landing system at Newark Airport. As long ago as 2001, a US DoT report said that GPS was a tempting target for adversaries. The professor, over a time, developed a spoofing system which could override the timing systems used by mobile-phone networks, electrical grids, and trading programmes. A C4ADS report in 2019 revealed that 10,000 spoofing incidents at sea between February 2016 and November 2018 affected about 1,300 vessels. The article warns that the other rivals to the original GPS system share similar vulnerabilities.