Gleaming trails of bomblets in night sky have become familiar to Israelis as Tehran exploits apparent vulnerability

• Middle East crisis – live updates

On 5 March, a post appeared on the X account of Iran’s late supreme leader, Ali Khamenei, managed by his staff after he was killed in an Israeli airstrike on 28 February. The tweet featured a stark piece of propaganda: a gleaming, oversized missile arcing across the sky as a city below is engulfed in flames. The caption read: “Khorramshahr moments are on the horizon.”

The Khorramshahr missile, Iran’s most advanced ballistic missile, is believed to be capable of carrying a cluster warhead dispersing up to 80 submunitions. Since that post, it has come to loom large in Israeli threat assessments, a persistent concern for a country equipped with a multi-layered missile defence system that is widely regarded as the world’s most sophisticated.