Hamas’s military operation of 7 October 2023 against Israel fundamentally challenged Tel Aviv’s prior assumptions regarding the sufficiency of its early-warning systems, border defenses, deterrent posture, and capacity to contain the Hamas threat. This study addresses the core question of how this event has transformed Israel’s threat perception and security identity vis-à-vis Hamas, and analyzes the resulting discursive shift. Methodologically, the article employs a qualitative approach based on thematic analysis. Data were collected through purposive sampling of official and publicly available documents issued by the Israeli Prime Minister’s Office, the Knesset, the Israel Defense Forces, and the government between 7 October 2023 and 21 August 2026. The findings indicate that, within Israel’s official discourse, the 7 October incident was represented as a strategic rupture and a “fivefold crisis” encompassing early warning, threat assessment, defense, deterrence, and citizen protection. This perceptual crisis precipitated a redefinition of Hamas—from a “containable, fragmentary threat” to an “existential, militarized, governing actor with self-regenerative capabilities.” Consequently, Israel’s declared security objectives evolved from the “periodic management of threat” toward the “complete destruction of Hamas’s military capabilities and governmental structures,” “unyielding opposition to its organizational reconstruction,” and a “fundamental reconfiguration of the threat environment.” The article concludes that this transformation does not signify a wholesale replacement of Israel’s security doctrine, but rather its recalibration and reordering to realize “active security,” a “prevention-oriented doctrine,” and the “maximal guarantee of strategic freedom of action.”