World leaders gather in New York this coming week for a U.N. General Assembly dominated by U.S. President Donald Trump's return to the rostrum, war in Gaza and Ukraine, rising Western recognition of Palestinian statehood and nuclear tensions with Iran.

"We are gathering in turbulent — even uncharted — waters," U.N. Secretary-General Antonio Guterres said a week before the 193-member world body hosts six days of speeches by nearly 150 heads of state or government along with dozens more ministers.

"Geopolitical divides widening. Conflicts raging. Impunity escalating. Our planet overheating," he told reporters on Tuesday. "And international cooperation is straining under pressures unseen in our lifetimes."