How effective can the missile defense system be?

This is a bullet-to-bullet high-tech technology, which has not been practiced in the United States. All the defense achievements or training achievements of the defense missiles it shows are arranged in advance. During the drill, the defenders already knew the data of when and where the attacker's missile took off, what the target was, how the missile trajectory was, and how fast it was. It was normal to shoot it down, but it was strange that it could not be shot down.

If you don't know where the other side is, when and where to fight, then the role of the anti-missile system is very debatable. It is said that the breakthrough probability of Russian Poplar -M missile is 80%. If this is true, the most advanced DF-4 1 in China should also have a 60% probability. Moreover, at present, missiles generally use supersonic flight, high-altitude orbit change, terminal snake maneuver and warhead separation, which not only greatly increases the penetration probability, but also increases the strike power and weapon deterrence. For example, a missile with 20t equivalent and two sub-warheads can produce more explosive power than a missile with 100t equivalent warhead. So if I always have 1000t equivalent of nuclear material, I can have greater nuclear strike capability.

One more thing, America's defense system is not fully integrated. For example, the aegis system in the United States can only defend against terminal guidance. For example, the Aegis ship deployed by the United States in Osaka, Japan, can only defend against missiles that hit Osaka, not against missiles that hit Hokkaido, and not against missiles that hit the United States.

In addition, for missile defense, it is better to attack the economy with missiles. The ratio of missile attack and defense consumption is about 1: 6, even reaching 1: 8. The United States wants to successfully intercept most of the high-density, multi-wave missile attacks of the other side, not to mention the technical failure. It is enough for the United States to spend money.