Ballistic missiles are making a comeback in the twenty-first century because they give countries like China, Iran, North Korea and Russia the ability to strike targets hundreds or thousands of miles away without having to expose vulnerable warplanes to interception. The precision allowed by modern guidance systems allows even non-nuclear missiles to deliver highly-deadly attacks against airbases, fuel and ammunition depots, and even moving aircraft carriers.
Therefore, the ability to intercept ballistic missiles is also growing in importance. But surface-to-air missiles (SAMs) designed to shoot-down aircraft struggle to hit missiles flying many times faster and higher. And the further a ballistic missile can go, the faster and higher it must fly, and the harder it becomes to intercept.
The United States has developed a spectrum Anti-Ballistic Missiles (ABMs)s, from the Patriot PAC-3 MSE which can intercept tactical ballistic missiles, the high-flying THAADS and naval SM-3 Block II missiles which can counter short to intermediate-range systems, and GMD interceptors in Alaska that can tackle intercontinental-range missiles.
Several European countries have caught up with lower-tier ABMs by developing a versatile SAM of which arguably exceeds the Patriot missile in capability—and may evolve a similar capability to THAADs.