TEHRAN - At 3, July 19 -- 39 in the morning on Sunday, projectiles fired by United States forces struck the Darkhovin Nuclear Power Plant under construction in Iran's southwestern Khuzestan province, according to a formal statement issued by Iran's Atomic Energy Organization. It was the first confirmed strike on a nuclear facility in the nine days of aerial operations Washington has conducted against Iran since July 8, and it crossed a threshold that international law has treated as categorically different from other military targets for decades.

The AEOI condemned the strike in terms that left no ambiguity about how Tehran intended to frame it internationally. "The terrorist and criminal US regime," the organization said, had attacked a...