DUBAI, June 10 -- In the Bamani district near Sirik, on Iran's southern coast, the taps ran dry on Tuesday. Two reservoirs that fed the area had been hit in an American airstrike, and the water that families there depend on went with them.

The strikes opened a new and more direct phase of a war that, only a day earlier, both Washington and Tehran had described as winding down. US Central Command said its forces began launching what it called self-defense strikes against Iran at 5 p.m. Eastern time, at President Trump's direction, in retaliation for the downing of a US Army Apache helicopter off the coast of Oman.

What had been a fight waged mostly at sea and in the air, through intercepted drones and contested patrols, has now moved ont...