Iran's Assembly of Experts has chosen Mojtaba Khamenei to replace his late father, Ayatollah Ali Khamenei, as the country's new supreme leader.
Israeli military carried out a further "wave of extensive strikes" against Iran overnight.
Explosions were heard across Gulf states, with at least 32 injured in Bahrain during an Iranian drone attack, according to state media.
US military base near Erbil Airport in Iraq was reportedly attacked by an Iranian drone.
Another US service member has died in the war with Iran, bringing America’s death toll to seven.
Iranian President Masoud Pezeshkian vowed to step up attacks on US targets across the Middle East, saying, "When we are attacked, we have no choice but to respond."
Donald Trump indicated he has no timetable for the Iran war, telling reporters, "I never project that—whatever it takes."
Trump also made it clear that Iran’s new supreme leader is “going to have to get approval” from the United States, and “if he doesn't get approval from us, he's not going to last long.”
Omani Foreign Minister Badr Albusaidi condemned US and Israeli attacks against Iran as "both immoral and illegal," but added that Iran's retaliation against neighboring countries is "deeply regrettable.”
Iranian Foreign Minister Abbas Araghchi said that before his country could even consider a ceasefire, the US and Israel “have to explain why they started this aggression."