As key allies turn away and war costs soar, the US military campaign against Iran is spurring a growing consensus among Chinese observers and state media – that Washington’s unrivalled global dominance is crumbling.

Communist Party mouthpiece People’s Daily issued a sharp critique on Thursday, warning that the United States’ shift from an “international rule-builder” to a “predatory hegemon” would ultimately undermine its prosperity and influence.

“In the post-Cold War era, while the...