Friday and Saturday kick off what will be up to a week of solemn funeral observances for slain Iranian Supreme Leader Ayatollah Ali Khamenei - a major historic event which is expected to draw some 15 to 20 million mourners in Tehran and across Iranian cities.Iran on Thursday issued a warning to the United States and Israel, Reuters reported:"We warn the enemies of Iran, especially the U.S. and the Zionist regime (Israel), to avoid any miscalculation and to think about the harsh retaliation our armed forces would make to any threat and aggression against our country," Ali Abdollahi, commander of Khatam al-Anbiya Central Headquarters, said in a statement carried by state media.Coffins containing Ayatollah Ali Khamenei & members of his family at a mosque in Tehran, after their deaths during the opening of the US-Israeli 'Operation Epic Fury'. Getty ImagesThe funeral procession events are expected to extend all the way to July 9, upon which the late Ayatollah will be buried in his hometown of Mashhad. Qom, as well as Shia centers in Iraq will also observe large-scale funeral events.Delegations representing various governments in the region have begun arriving in Tehran on Friday to pay their respects, though the Iranian government has made clear that no European governments were invited.There has already been some surprises, with Reuters reporting that Saudi Deputy Foreign Minister Waleed El Khereiji and his delegation have showed up in Tehran to pay their respects - though they weren't officially expected, per Iranian state publications...⚡️BREAKING: Unexpected arrival of Saudi Arabia's Deputy Foreign Minister at the funeral ceremony of Ayatollah Khamenei