How far can Iran’s ballistic missiles reach? A defense expert explains how the missiles work, and what Iran can and can’t hit

Iran fired two ballistic missiles at Diego Garcia, a joint U.S.-U.K. military base in the Indian Ocean, on March 20, 2026, though Iran has denied responsibility for the launches. One missile broke apart in flight and the other was destroyed by U.S. missile defenses, suggesting Iran attempted to strike a target 2,500 miles away—roughly twice the maximum range it has declared for its ballistic arsenal. Experts believe the missiles were likely modified versions of Iran's Khorramshahr intermediate-range system with reduced warheads to extend range, though the failure indicates Iran may be operating these weapons beyond their reliable capability. The successful U.S. interception and the missile malfunction suggest Iranian intermediate-range ballistic missiles do not pose a significant military threat despite their theoretical reach into Western Europe, Asia, and Africa.