Since the UN was founded in October 1945 amid a burst of idealism in the aftermath of the second world war, its cannier leaders have understood that their principal power stemmed from the pulpit: they can publicly shame and scold the member states.

Dag Hammarskj?ld, the flamboyant second secretary-general, who died in a mysterious plane crash in 1961 while mediating in the Congo, was the most artful exponent of this approach. When he spoke, the world listened. It was he who uttered the words that on the UN’s better days still enshrine its mission. “The UN was created not to lead mankind to heaven,” he said. “But to save humanity from hell.”

The current secretary-general, the more cautious António Guterres, likes on occasion to maintain that tradition of speaking out. Last week he summoned a press conference at the UN headquarters and lacerated Israel over its offensive in the Gaza strip. His language was stark and stripped of trademark UN diplomatese.