TEHRAN — Iran's supreme leader, Ayatollah Mojtaba Khamenei, urged Gulf rulers in a written message on Sunday to identify their "real enemy," understand its plans and confront it. The message, marking the birthday of Islam's Prophet Muhammad's birthday and published on Khamenei's Telegram account, also called for unity, mutual defence against "enemies" and cooperation among Muslims worldwide. Khamenei has not been seen in public since being injured in the U.S.-Israeli airstrikes six months ago that launched the war, killing his father and previous supreme leader, Ayatollah Ali Khamenei.