A hypersonic missile launched under nuclear shadow can reach its target before governments have fully decided what they are seeing, who is in danger, or whether a defensive move will calm the crisis or widen it. Classical deterrence still requires survivable retaliation, credibility, signalling, and escalation control. Under severe time compression, those foundations no longer suffice on their own.
Shlomo Kashani develops two linked theories—hypersonic deterrence under compression and bounded protective defence—to explain when a defensive fourth leg can preserve stability and when the same capability produces the crisis it was meant to prevent.
Four quantified war games place that argument under pressure across India–Pakistan, United Kingdom–Russia, United States–North Korea, and escalation towards general nuclear war. They use declared flight-time ranges, matched controls, six decision gates, and casualty and damage ledgers. They are executable open-source designs, not reports of exercises already conducted.
The proposed fourth leg is not a promise of invulnerability. It joins assured retaliation to warning, sensing, interception, shelters, continuity, alliance coordination, and tightly governed hypersonic roles. Its purpose is to preserve usable choice: enough time to interpret, protect, consult, and keep nuclear decisions under lawful authority.
The argument is deliberately conditional. Strip away transparency, civilian protection, alliance discipline, and strict limits on missions, and protective speed becomes pre-emption by another name.