A hand grenade will do little damage to a vehicle protected by an inch of steel plate, David Hambling explains (in Swarm Troopers), but high precision and intelligent targeting make an effective substitute for brute force:
In the 1991 Gulf War, laser-guided Mk 82 bombs weighing five hundred pounds were used for “tank plinking” attacks against individual Iraqi tanks. Unlike in previous wars when dozens of bombs were needed to guarantee a hit on such a small target, laser guidance meant that a pilot could score four kills with four bombs. The bombs were accurate enough, and a bomb of this size was overkill even against heavily-armored Russian-made T-72 battle tank.
In the 2003 war in Iraq, the Hellfire missile weighing a fifth as much proved just as efficient at destroying tanks. Laser guidance meant that every shot was likely to find its mark.
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The T-72 has frontal armor more than eighteen inches thick, and the Hellfire can punch through it. But tank armor is not distributed evenly.
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The AT4’s warhead weighs just under a pound, and it is capable of penetrating an impressive fifteen inches of armor compared to three inches for the original bazooka. This is still not enough to take a T-72 head on — tank armor is specifically intended to defeat this sort of threat — but it means the soldier can tackle anything else on the battlefield.
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From above, the T-72 is a much easier prospect. The large, flat surface of the top of the tank has comparatively thin armor; if it was as thick as the front, the tank would be too heavy to move. The top armor on the T-72 is around two inches thick, and there are spots where it is even weaker.
While a small charge can breach the armor, the damage it does — the “behind armor effect” — is limited. One soldier compares it to firing a bullet through a car — alarming for the people inside but not likely to cause real damage. The high-speed jet of metal will injure anyone it hits and may set off fuel or explosives, but in a vehicle the size of the T-72, most shots will do little harm. That happens when the shot placement is more or less random, as it is likely to be in battle using an unguided weapon like the AT-4, often at long range against a target that may be moving. In practice it usually takes multiple hits from this sort of weapon to stop a tank.
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Current guided weapons sense a target and tend to aim approximately at its center of mass. (A major exception is heat-seeking missiles, which home in on hot exhaust pipes). As we have seen, a small drone has enough computing power to do something much more sophisticated.
As the weapons get more efficiently lethal, maybe studying a strategy for avoiding stupid wars is a good idea.
I mean, not that WMD was a lie.