India, March 9 -- Seyyed Mojtaba Hosseini Khamenei, the son of slain Iranian Supreme Leader Ayatollah Sayyed Ali Khamenei, has been appointed the new Supreme Leader of the Islamic Republic of Iran, state television announced early Monday, marking a dramatic political development as the war triggered by his father's assassination is rattling the world.

Iran's Assembly of Experts, an 88-member body constitutionally tasked with selecting the Supreme Leader, elected the 56-year-old cleric in a decisive vote late Sunday night. The assembly said Mojtaba Khamenei had been chosen with "strong votes" and called on the nation to unite behind the new leader during the ongoing crisis.

"By a decisive vote, the Assembly of Experts appointed Ayatollah...