Today guided weapons can use a combination of INS, GPS and radar terrain mapping to achieve extremely high levels of accuracy such as that found in modern cruise missiles.

Can missiles be tracked?

The Space Tracking and Surveillance System (STSS) is a space-based system developed and operated by the Missile Defense Agency (MDA) that detects and tracks ballistic missiles.

Does Icbms use GPS?

They used inertial navigation systems, much like jetliners still do to supplement GPS.