Iran fired two ballistic missiles on March 20, 2026, at the Indian Ocean island of Diego Garcia, which hosts a strategically important joint U.S.-U.K. military base, according to U.S., U.K. and Israeli officials. One missile broke apart during flight, and the other appears to have been destroyed by U.S. missile defenses.

Iran has denied responsibility for the launches.

Diego Garcia is about 2,500 miles (4,000 kilometers) from Iran, which is about twice as far as the top range Iran has declared that its ballistic missiles have. Parts of Western Europe, Asia and Africa lie within a 2,500-mile (4,000-km) radius of Iran, raising concerns about the vulnerability of these areas.

However, there’s no evidence that Iran has developed a new type of missile or that it can otherwise hit targets at the longer range. Iran most likely modified an existing type of missile, but increasing a missile’s range poses significant challenges.

Ballistic missile basics

A ballistic missile is launched on a rocket and, after separating from it, subsequently flies mostly under the influence of gravity to its destination. The name refers to the characteristic arc of projectiles whose trajectories are largely shaped by gravity. The range of these missiles is determined by the size of the rocket.

Short-range ballistic missiles can fly about 300 to 600 miles (500 to 1,000 km) and can be launched from mobile trucks. They are used for destroying key defensive infrastructure such as radars.

Medium-range ballistic missiles have ranges of about 600 to 1,800 miles (1,000 to 3,000 km). They are used to attack more strategic targets such as command and control centers where military leaders........

© The Conversation