Israel's unprecedented strikes on Iran, which have killed top military leaders and nuclear scientists, required years of meticulous intelligence gathering and infiltration, experts say.

Shapiro served as Deputy Assistant Secretary of Defense for the Middle East until January—charged with, among other things, considering scenarios in which tensions between Israel and Iran escalated into all-out war and preparing U.

The two powers have been exchanging barrages since Israel attacked Iran and killed many of the country’s top military leaders and scientists.