Changes

====Space-based systems====

====Space-based systems====

Space-based systems generally aim to destroy a ballistic missile at the height of its trajectory.

Space-based systems generally aim to destroy a ballistic missile at the height of its trajectory.

At this point, the missile is fragile and vulnerable.  The difficulty lies in detecting the object, deploying the countermeasure, and successful interception.  Several solutions have been proposed, including so-called "smart rocks" and "smart pebbles" which would be non-ballistic objects deployed to intercept the missile, and at low-energy, deflect or destroy the ICBM.

At this point, the missile is fragile and vulnerable.  The difficulty lies in detecting the object, deploying the countermeasure, and successful interception.  Several solutions have been proposed, including "Brilliant Pebbles", which would be non-ballistic kinetic missiles deployed to intercept the missile, and at low energy, deflect or destroy the ICBM.

==Criticisms==

==Criticisms==