After addressing Hamas’s intelligence collection in previous chapters, this chapter focusses on Hamas’s efforts to counter Israeli intelligence efforts against it. To overcome Israel’s attempts to infiltrate its ranks, Hamas went to great lengths to screen those wishing to join it, while diligently acting to detect collaborators with Israel, both within its ranks and in the broader society in which they operate, while applying internal compartmentalization to the organization. To counter Israel’s SIGINT activity, Hamas tried to avoid the use of wireless communications, and also made use of encryption, both in telephone communication and in correspondence; over time, Hamas developed an internal communication system that is separate from the public system. To defeat Israel’s GEOINT efforts, Hamas tried to conceal its activities to the greatest extent possible. This included a range of strategies, including camouflage, the assimilation of military installations in civilian surroundings, and the use of subterranean spaces. Regarding open-source media publications, Hamas developed the awareness of the need to impose censorship to hide certain characteristic signs of its activity.