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.

The latest attack using cluster munitions occurred on Sunday, when an Iranian ballistic missile struck central Israel, injuring 15 people.

According to the Israel Defense Forces, roughly half of the missiles launched from Iran since the escalation have carried cluster warheads.

The Guardian, which reviewed the impact of dozens of Iranian strikes alongside statements from Israeli officials, has identified at least 19 ballistic missiles carrying cluster warheads that penetrated Israeli airspace and struck urban areas since the beginning of the war with Iran on 28 February. Those attacks have killed at least nine people and wounded dozens, reflecting a broader shift in Iran’s tactics that appears to have exposed a vulnerability in Israel’s air defences. Since the start of the war, Iran’s cluster munitions – which disperse dozens of bomblets mid-air – have tested Israel’s highly advanced, multi-tier missile defence network, including Iron Dome, which is designed to counter threats across ranges, altitudes and speeds, exposing gaps that interception alone has struggled to close.