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.

Iranian officials have repeatedly denied seeking a nuclear weapon. The United States and Iran have held five rounds of negotiations toward achieving an agreement that would limit Iran's nuclear activities in exchange for sanctions relief, with a sixth round of talks scheduled for Sunday.

Israel's Prime Minister Benjamin Netanyahu says his country will strike "every site and every target of the ayatollah regime" in Iran.