JERUSALEM, April 19 — More than six months of Israel’s military offensive in Gaza has turned the Palestinian territory into a “humanitarian hellscape,” UN chief Antonio Guterres said Thursday, also warning that one wrong move could see the Middle East devolve into wider war.

World powers have been watching nervously since Israel vowed to retaliate against Iran for its unprecedented weekend assault on its arch enemy, with fears soaring that escalating tit-for-tat attacks could push the region towards broader conflict.