Ballistic Missile

A ballistic missile is powered for only the first minutes of flight. Its rocket burns out, and the missile then coasts on a high arcing trajectory, like a thrown stone, ballistic in the physics sense, until gravity brings the warhead down at speeds that can exceed 20 times the speed of sound for the longest-ranged types. That flight profile is the defining trade: enormous speed and reach, bought at the price of a largely predictable path.

The range ladder

Classification runs by reach, and the categories carry treaty and policy weight. Short-range ballistic missiles (SRBM, under 1,000 km) include the Iskander and ATACMS class that Ukraine made familiar. Medium- and intermediate-range missiles (1,000 to 5,500 km) were banned for the US and Russia between 1987 and 2019 under the INF Treaty, and their return is reshaping Pacific and European force planning. Intercontinental ballistic missiles (ICBM, above 5,500 km) exist for one job, nuclear deterrence, flown from silos, road-mobile launchers, and submarines. The submarine-launched leg matters most to stability arguments, since a boat hidden in the ocean guarantees retaliation no first strike can prevent.

Modern designs blur the clean arc. Maneuverable reentry vehicles, depressed trajectories, and hypersonic glide vehicles that ride a ballistic boost then skim and steer through the upper atmosphere all exist to defeat the defenses that predictability invited. Precision conventional ballistic missiles changed the conversation too: China's DF-21D anti-ship variant aims at moving carriers, and Iran's 2024 salvos against Israel were the largest conventional ballistic attacks ever flown, instructive on both what saturation achieves and what layered defenses stop.

Defense, and its limits

Intercepting a ballistic missile means hitting a small object traveling kilometers per second, and the fielded systems divide by layer: Patriot and THAAD for the terminal and upper-terminal layers, Aegis SM-3 for midcourse above the atmosphere, and the US Ground-based Midcourse Defense for limited ICBM threats. The economics run against the defender, interceptors cost more than most attacking missiles, and the physics runs against defending everywhere at once. Israel's multi-tier network is the working proof that defense is possible against regional arsenals, and the standing caveat is that nobody has faced a full peer salvo.

How is this different from a cruise missile?

A cruise missile is an unmanned jet aircraft: powered the whole way, flying low and maneuvering, hours to arrive, hard to detect. A ballistic missile is a bullet: minutes to arrive, hard to stop. Arsenals hold both because defenders must then solve two opposite problems at the same time, and the combined salvo, ballistic to open the door, cruise and drones through the gap, is now standard offensive practice.