I agree that the full explosion is the least likely outcome, but it still very possible. Cruise missiles are intercepted by a rocket exploding in front of it.

I agree that the full explosion is the least likely outcome, but it still very possible. Cruise missiles are intercepted by a rocket exploding in front of it. As we know (for example from the MH17 investigation) - the major damage is done by shrapnel from the intercepting rocket. The level to which the incoming missile is damaged by shrapnel will very - it can be very slight damage by just a few elements, or a very heavy one. We don't know how the nuclear warhead is configured. It is sensible to predict, that the detonation mid-air over enemy territory is the desired outcome. So the light damage may start the detonation sequence by design. Hypersonic missiles are much harder to destroy because the timing needs to be much more precise. It means that the rocket may receive much lighter damage, which increases the chances of starting the detonation sequence and exploding before hitting the ground.