New Delhi, March 3 -- Israel's assassination of Iran's Supreme Leader Ayatollah Ali Khamenei was not a sudden tactical breakthrough but the culmination of a years-long intelligence operation that penetrated Tehran's surveillance infrastructure, mapped the daily routines of his security detail and exploited vulnerabilities in the capital's communications grid, according to a Financial Times exclusive.

The operation, which officials describe as a fusion of cyber intrusion, human intelligence and advanced data analytics, enabled Israeli and US intelligence agencies to determine with precision when the 86-year-old leader would be present at his offices near Pasteur Street - and who would be with him - before launching the fatal air strike. ...