The defense against the cruise missiles is more challenging and difficult since they remain in the atmosphere during all their flight time at low altitude. Currently, the United States has different anti-cruise missiles including the Standard Missile-2, Standard Missiles-6, Medium Extended Air Defense System (MEADS), and Evolved Seasparrow Missile (ESSM) systems. These systems are designed for supersonic cruise missiles.
But here we are talking about Hypersonic missiles.
In recent defense expo at New Delhi by Ministry of Defense, HTNP Industries co-founders Saurav L. Chaudhari and Shantanu P Gawande explained the liabilities of Hypersonic missiles by saying " Hypersonic missiles aren't something we called as ultimate weapon "
They can be stated as fallows:
1) Massive Guidance Sensor Degradation. At hypersonic speeds, the leading edges of the vehicle become superheated and produce either plasma or ionized gases. Much like signal blackout during re-entry, this effectively blinds on board active sensors, so hypersonics will most likely not have them, the will rely on receiving targeting data via trailing edge antennae from distant sensors (satellite, aircraft, etc) and the farther away those sensors are, the easier they are to blind or spoof, and the less accurate they will be. The kill-chain requires “eyes-on” real-time guidance from multiple distant line-of-sight signal sets. This offers more chances to defeat the chain.
2) Poor Terminal Guidance and Limited Maneuverability. Hypersonics are going to be awful at hitting moving targets. By virtue of their speed, small deviations in their flight profile can change their terminal path by a kilometer or more. They simply will not be able to course correct at all during the last few seconds of flight, the tolerances are simply too large. Small gusts of wind and slight variations in air pressure and temperature will affect the flight path by a hundred meters or more. Anyone who says these are maneuverable vehicles is full of BS. Ask an SR-71 pilot if they ever dared a turn at Mach 3+. Whatever maneuvers they may do will be entirely programmatic, not active or autonomous.
3) Poor Kinetic Stability and Thermal Vulnerability. As stated above, at such speeds, precision is an illusion. It is like aiming a gun at the target on a clothesline on a lightly breezy day, closing your eyes, pulling the trigger and hoping to hit the bullseye. Speed works both ways. If the target stays where it is or is expected to be, and your positional awareness remains perfect, and the breeze stops you have a decent chance. If any of those change a tiny bit, your chances fall to near zero. The problem is that the defender can affect all of those. A warship could change the air density in front of the vehicle and destroy it, and there are many ways to do it. A thermal airburst in the path of the vehicle would create massive fluctuations in air density and a shockwave that would ruin whatever solution was in play. At sea level a thermal burst would flash steam which is dense and rising, and this would alter the trajectory by hundreds of meters. The same could be achieved by CIWS filling the air with ocean spray, or chaff comprised of thermite or liquid nitrogen dispensors. The thermal turbulence in the air will ruin any targeting in play. A puff of sand would be enough to destroy the vehicle given the massive kinetic energy.
4) Easy To Track. By virtue of their superheated titanium (non-stealth) airframe and massive supersonic pressure wave, these weapons will light up the Infrared and Doppler like an effing Christmas Tree. Yes, the warning time is shorter, but the signature will be unmistakeable if your software is tuned to recognize it and you cannot effectively jam long range IR and simple doppler radars. A weather radar with the right software would see this thing coming.