How do nuclear missile defense systems account for countermeasures and decoys used by incoming missiles?

Countermeasures and decoys are methods used by an attacking missile to deceive a missile defense system by making it difficult to identify the real warhead from among the decoys. In response, nuclear missile defense systems use a range of technologies to counter these threats. One of the main ways to counter decoys is to use multiple sensors and detection systems to increase the chances of detecting the real warhead. For example, radar and infrared sensors can be used t....