Defending against hypersonic weapon delivery systems

Defense Maven:

DARPA Builds Advanced Interceptor Weapon to Destroy Hypersonic Missile Attacks

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DARPA, the Pentagon's pet research agency, wants an interceptor that can stop weapons that are hypersonic (travel faster than Mach 5). The agency has begun soliciting proposals for Glide Breaker , its project to stop boost-glide vehicles that are lofted high into the atmosphere atop a ballistic missile, and then glide down to Earth. The current exemplar is Russia's Avangard, touted by President Vladimir Putin as unstoppable by anti-missile defenses. The Avangard is lofted by a giant RS-28 Sarmat ICBM, and then glides down to its target at Mach 20. But China and the U.S. are also developing boost-glide vehicles.

DARPA seeks to "develop and demonstrate a technology that is critical for enabling an advanced interceptor capable of engaging maneuvering hypersonic threats in the upper atmosphere." And it wants this technology in a hurry: Glide Breaker should be tested in 2020. Meanwhile, the Missile Defense Agency -- the Pentagon organization charged with stopping ballistic missiles -- also has its program to develop defenses against hypersonic weapons.

There's a reason for the rush. Hypersonic weapons may be able to penetrate U.S. missile defenses or streak past the defenses of U.S. aircraft carriers. Even more worrisome, they might be armed with conventional warheads to destroy targets -- notably ICBMs in hardened silos -- once thought invulnerable to anything but nuclear weapons.
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Putin's brag about the missiles being unstoppable appears to have been based on a lack of imagination at the creativity of US defense scientists.  History has shown that whenever new weapons are developed there will be innovation to deal with them.  Hypersonic weapons are inherently unstable and subject to being nudged into self-destruction.