Israel unleashed a punishing wave of strikes across the breadth of Iran on Sunday and Tehran hit back with fresh missile barrages, as both sides threatened more devastation in a conflict that appeared to be intensifying.

After decades of enmity and a prolonged shadow war fought through proxies and covert operations, the latest conflict marks the first time the arch-enemies have traded fire with such intensity, triggering fears of a lengthy conflict that could engulf the entire Middle East.

Israeli authorities told citizens to head to shelters in advance of incoming missiles Sunday, while Iran said it would begin opening mosques, metro stations and schools to serve as makeshift refuges as Israel kept up its withering strikes.

Israel says its attacks have hit military and nuclear facilities, and killed top officers and atomic scientists, but a senior US official said Sunday that President Donald Trump had told Israel to back down from a plan to kill supreme leader Ayatollah Ali Khamenei.

Meanwhile, residential areas in both countries have suffered deadly strikes since the hostilities broke out two days ago, with Netanyahu on Sunday slamming Iran for allegedly targeting civilians.

"Iran will pay a very heavy price for the premeditated murder of civilians, women and children," he said during a visit to the site of a missile strike on a residential building in the coastal........

© Al Monitor