Which of the following is a measure taken under Active Air Defense?

The destruction of hostile missile installations is a definitive action taken under Active Air Defense. This approach focuses on directly engaging and neutralizing threats before they can cause harm. Active Air Defense encompasses offensive operations aimed at preventing enemy attacks, which includes targeting and eliminating missile sites that pose a risk to friendly forces and assets. This is a proactive measure that enables a defensive posture by reducing the capabilities of potential aggressors.

Other options, while they may relate to overall defense strategies, do not fit the definition of Active Air Defense as closely. Countermeasures against enemy deception, for example, are more aligned with tactical awareness and information operations rather than direct engagement. The construction of shelters is a passive defense measure meant for protection, and the use of new camouflage technologies mostly pertains to concealment rather than active engagement with threats. Thus, the focus on directly neutralizing hostile missile installations solidifies why this answer aligns correctly with Active Air Defense measures.