U.N. Secretary-General António Guterres is warning that impunity, inequality and uncertainty are creating an “unsustainable world” where a growing number of countries believe they should have a “get o

Facing a swirl of conflicts and crises across a fragmented world, leaders attending this week’s annual U.N. gathering are being challenged: Work together — not only on front-burner issues but on modernizing the international institutions born after World War II so they can tackle the threats and problems of the future.