After assassinating a top Hamas commander, Muhammed Sinwar, in May 2025, the Israeli military sent a special unit into an underground complex he had used. There, they found a computer unconnected to a network — and much harder to access by Israeli operations spying on Hamas communications. The computer held an image of a six-page memo, handwritten in Arabic, that the Israeli intelligence community believes was by his brother Yahya Sinwar, who as the powerful leader of Hamas in Gaza helped plot the Oct. 7, 2023, attack on Israel. Dated Aug. 24, 2022, it appears to be a directive from...