UNITED NATIONS (AP) — With rising unilateralism challenging its very existence, the United Nations convenes its annual meeting of world leaders Monday and will try once more to tackle problems together as a community of nations, addressing threats ranging from Mideast conflicts to the effects of global warming — and also encouraging the glimmer of hope over the nuclear standoff in North Korea.

This year, 133 world leaders have signed up to attend the General Assembly session, a significant increase from last year's 114. Secretary-General Antonio Guterres called the expected large turnout "eloq...