MLA standing for InfraRed CounterMeasures.
Infrared radiation is part of the electromagnetic spectrum, and is emitted by heat sources, such a engine exhausts and humans. It can be detected by suitable electronics and is therefore useful in targeting. This has resulted in countermeasures being developed, i.e. IRCM.
Infrared detecting technologies can be used to allow soldiers, especially tank commanders, to see an enemy through smoke or in the dark. The energy is detected and projected as a false colour image on a computer screen. Little can be done to counter such passive observation technologies. The old technique of hiding in a compost heap might be useful for Them, but a whole platoon of advancing compost heaps is likely to arouse suspicion.
Air-to-air and ground-to-air missiles often use infrared tracking to home onto an aircraft’s exhaust. They can be thrown off course if the target fires off something hotter, such as a flare. Almost all modern combat aircraft are equipped with such countermeasures. More advanced aircraft mounted IRCM systems use a modulated infrared signal to disrupt the missile’s seeker circuitry and so cause it to break target lock.
A wokka deploying compost: