Israel’s use of Tehran street cameras to help kill Iran’s supreme leader shows how everyday surveillance can turn into a wartime weapon. On Feb. 28, Israel exploited hacked city camera feeds to track Ayatollah Ali Khamenei. Hundreds of millions of cameras have been installed above shops, in homes and on street corners across the world, many connected to the internet and poorly secured. Recent advances in artificial intelligence have enabled militaries and intelligence agencies to sift through vast amounts of surveillance footage and identify targets.