How does ATIRCM protect aircraft from IR guided missiles?

The choice that describes how ATIRCM (Advanced Threat Infrared Countermeasures) protects aircraft from infrared-guided missiles is using laser energy disruption. This system employs high-intensity laser beams to create a bright distraction, which effectively confuses the missile's infrared seeker, thus preventing it from locking onto the aircraft. By manipulating the missile's guidance system, ATIRCM can protect the aircraft from potential threats.

The other options do not adequately describe the specific functionality of ATIRCM. Enhancing radar sensitivity pertains to improving detection capabilities and does not relate to defending against infrared-guided threats. Increasing altitude can provide a tactical advantage but does not utilize technology specifically designed to counter infrared-guided missiles. Finally, using smoke screens is a tactic that may obscure visibility but lacks the precise targeting disruption capabilities that laser energy provides. Hence, the choice of laser energy disruption accurately reflects the operational mechanism of ATIRCM in protecting aircraft.