Countermeasures
Countermeasures against ATGMs include spaced, perforated, and composite armour, explosive reactive armour, jammers like the Russian Shtora, and active protection systems (APS) like the Israeli Trophy and the Russian Arena.
Armour systems have continued in development alongside ATGMs, and the most recent generations of armor are specifically tested to be effective against ATGM strikes, either by 'tricking' the missile into not detonating against the armor itself (such as in Slat Armour) or using some form of reactive armor to 'attack' the missile upon impact, disrupting shaped charge that makes the warhead effective. Both come with the downside of significant weight and bulk. Reactive armor requires a vehicle be specifically designed with the system integrated and while developments continue to make armor lighter, any vehicle that includes such a system necessitates a powerful engine and will still be relatively slow. Slat armor is lighter and as such can be added to many vehicles after construction but still adds both bulk and weight. Particularly for vehicles that are designed to be transported by cargo aircraft, slat armor has to be fitted in field after deployment. Either approach can never offer complete coverage over the vehicle, leaving tracks or wheels particularly vulnerable to attack.
Jamming is potentially an effective countermeasure to specific missiles that are radar guided, however, as a general purpose defense, it is of no use against unguided anti-tank weapons, and as such it is almost never the only defense. If jamming is used continually, it can be extremely difficult for a missile to acquire the target, locking on to the much larger return from the jammer, with the operator unlikely noticing the difference without a radar screen to see the return. However, any missile that has a back up tracking system can defeat jamming.
Active protection systems show a great deal of promise, both in counteracting ATGMs and unguided weapons, but are not yet a proven technology. Compared to armor systems, they are very light weight, can be fitted to almost any vehicle with the internal space for the control system and could, in the future, be a near-perfect defense against any missiles. The weakness of the systems include potential developments in missile design such as radar or IR decoys, which would drastically reduce their chance to intercept a missile, as well as technical challenges such as dealing with multiple missiles at once and designing a system that can cover a vehicle from any angle of attack. While these may be answered and allow for light weight, highly maneuverable vehicles that are strongly defended against missiles and rockets that are extremely well suited for urban and guerrilla warfare. However, such a system is unlikely to be as effective against kinetic energy projectiles, making it a poor choice for fighting against tanks.
Traditionally, before "fire-and-forget" ATGMs were used, the most effective countermeasure was to open fire at the location where the missile was fired from, to either force the operator to take cover or kill himand thus making the missile go out of control and miss the target. While fire and forget missiles have definitive advantages in terms of guidance and operator safety, and include abilities such as top attack mode, older missiles continue in use, both in the front line armies of less developed countries, and in reserve service the world over, due to their lower cost or existing stockpiles of less advanced weapons.
Read more about this topic: Anti-tank Missile