One afternoon in late 2021, Microsoft’s chief executive, Satya Nadella, met with the commander of Israel’s military surveillance agency, Unit 8200. On the spy chief’s agenda: moving vast amounts of top secret intelligence material into the US company’s cloud.

Meeting at Microsoft’s headquarters near Seattle, a former chicken farm turned hi-tech campus, the spymaster, Yossi Sariel, won Nadella’s support for a plan that would grant Unit 8200 access to a customised and segregated area within Microsoft’s Azure cloud platform.

Armed with Azure’s near-limitless storage capacity, Unit 8200 began building a powerful new mass surveillance tool: a sweeping and intrusive system that collects and stores recordings of millions of mobile phone calls made each day by Palestinians in Gaza and the West Bank.