UNITED NATIONS (AP) — Facing an escalating nuclear threat from North Korea and the mass flight of minority Muslims from Myanmar, world leaders gather at the United Nations starting Monday to tackle these and other tough challenges — from the spread of terrorism to a warming planet.

The spotlight will be on U.S. President Donald Trump and France's new leader, Emmanuel Macron, who will both be making their first appearance at the General Assembly. They will be joined by more than 100 heads of state and government, including Zimbabwe's President Robert Mugabe, one of Africa's longest-serving lead...