New Delhi, June 8 -- The director general of the world's nuclear watchdog opened the IAEA Board of Governors meeting Monday with a blunt declaration that he said was directed at every combatant in every active conflict on earth: nuclear facilities are off-limits. No exception, no asterisk, no ranking of which plant matters more than another.

nuclear safety is fundamental and applicable to all, without exception," Rafael Grossi told delegations assembled at the agency's Vienna headquarters. "There are no double or triple standards here for the IAEA. An attack on any facility, wherever it is located, is unacceptable, a no-go, taboo."

The statement carried an implied geography even as Grossi insisted it applied universally. He had just ret...