Iran has learned a lesson from Israel’s bombing of Iraq’s Osirak reactor in 1981 and Syria’s nuclear reactor in 2007. Over the years, Tehran has deliberately dispersed key elements of its program across the country — placing some in hardened and deeply buried facilities — to make it difficult for an attacker to eliminate the program in a single strike. Tehran is also engaged in a concerted denial and deception campaign intended to obfuscate the status and location of its nuclear sites. Iran presents a significant intelligence challenge for its adversaries. Any would-be attacker would need to possess an accurate and comprehensive understanding of the program’s layout, the tactical capability to hit a large and protected target set, and the ability to manage the consequences of an attack.