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

Key Points:

• On March 20, 2026, Iran fired two ballistic missiles at the U.S.-U.K. military base on Diego Garcia in the Indian Ocean; one missile broke apart in flight and the other was intercepted by U.S. missile defenses, while Iran denied responsibility for the launches.
• Diego Garcia is about 2,500 miles from Iran, roughly twice the declared maximum range of Iran’s ballistic missiles, raising concerns about Iran’s missile capabilities and the vulnerability of regions within this radius, including parts of Western Europe, Asia, and Africa.
• Iran’s existing missile arsenal includes short-range and intermediate-range ballistic missiles, but there is no evidence Iran has developed new missile types capable of reliably striking targets at the longer range demonstrated by the Diego Garcia attack.
• Extending missile range involves significant technical challenges related to rocket size, payload capacity, structural integrity, and guidance accuracy, which likely limits Iran’s ability to field many reliable long-range missiles; the failure and interception of the missiles suggest operational limitations.
• The attack appears to be more symbolic and political than a credible military threat, as such costly and limited missile launches are vulnerable to advanced U.S. and allied air defenses, but the incident may increase international pressure for diplomatic efforts to resolve tensions with Iran.