Tehran, March 1 -- Thousands in Tehran, Isfahan, and Mashhad gathered to mourn Supreme Leader Ayatollah Ali Khamenei, killed in U.S.-Israeli airstrikes on Saturday, Islamic Republic of Iran Broadcasting (IRIB) reported.

Marking 40 days of public mourning, citizens chanted "God is great," paid tribute at holy sites, and protested the attacks, as Iran braces for a leadership transition and heightened national security.

In the central Iranian city of Isfahan, residents gathered at Imam Square to protest the strikes and to mourn what state media termed the martyrdom of Ayatollah Khamenei. Demonstrators raised slogans including "God is great" as the airstrikes continued.

Meanwhile, in the northeastern city of Mashhad, mourners gathered at t...