[nullhole]

As I understand it, hypersonics only got the focus they did in russia and china because US missile defence had evolved to the point where it was too much of a threat to existing ballistic missiles. No fundamental reason to think hypersonics won't in turn suffer the same fate.

[maxglute]

They transitioned to hypersonic development after US withdrew from ABM treaty in early 2000s, historically moving to hypersonic was not reaction to US having a working shield (it didn't), it was more proactive move demonstrate US pursuing missile shield is likely not ever going to be viable. It took another 15+ years for US ABM tests to consistently intercept ballistics, and even then under very favourable (scripted), not operational conditions, i.e. FTM44 in 2020 was first time US intercepted an "ICBM representative" target. Current US ABM defense #s is not remotely credible threat vs salvo medium/high end ballistics, i.e. current US has ~50 GMDs, it functionally doesn't matter for strategic level exchanges.

For theatre/tactical performance, again early Kinzhal was functionally ballistic and interception rate was ~25%, dropped to 6% when RU added some terminal maneuvering. So US has not only not caught up to ABM defense outside of North Korea tier threats, ABM defense currently on trend to lose the physics race (against capable adversaries). There are fundamental physical reason high end hypersonics will likely only extend the interception gap. The TLDR is terminal speed past mach 6+, the intercept window compresses so much it becomes almost mechanically impossible for interceptors, i.e. g-load on interceptors will physically break them apart. Kinzhal (which US/PRC categorize as ballistic tier) terminal is ~mach4, PRC DFs (US categorize as proper hypersonic) are estimated to sustain mach 5-10, i.e. high machs until final seconds, basically physically impossible engagement envelopes. DEW doesn't have dwell time vs hypersonic already shielded against plasma sheath. Current golden shield bet is on glide phase interceptors, which doesn't really answer magazine math, i.e. multiple expensive interceptors (especially midcourse) is going to lose the attrition game regardless, maybe not vs smaller adversaries, but vs PRC. Extra lopsided in context of naval defense with limited magazine depth where it's not even about $$$ but inability to defend against saturation.