Israel says preemptive airstrikes against Iran's nuclear sites are underway, and it is bracing to intercept a wave of drones launched by Iran in retaliation.

Multiple sources tell CBS News that Israel is poised to launch an operation on Iran. CBS News Middle East reporter Courtney Kealy has more.

The death toll grew Sunday as Israel and Iran exchanged missile attacks for a third consecutive day, with Israel warning that worse is to come. Israel targeted Iran’s Defense Ministry headquarters in Tehran and sites it alleged were associated with Iran’s nuclear program,

The Israeli military targeted Iranian nuclear facilities, research scientists and senior military commanders in dozens of preemptive airstrikes​.

Israel launched an expanded assault on Iran on Sunday, targeting its energy industry and Defense Ministry headquarters, while Tehran unleashed a fresh barrage of deadly strikes. The simultaneous attacks represented the latest burst of violence since a surprise offensive by Israel two days earlier aimed at decimating Tehran’s rapidly advancing nuclear program.