Issue Brief: Escalation risks of Hypersonic Boost-Glide vehicles

The United States, Russia, and China are developing a new generation of hypersonic weapons. The systems under development include both cruise missiles and glide vehicles that are launched by ballistic missiles. This issue brief focuses on hypersonic boost-glide vehicles (BGVs). Although alarmism is misplaced, BGVs could create new pathways for inadvertent escalation and present additional challenges for arms control. One of the key findings is, that indeed much of the alarm around BGVs is unwarranted. The deployment of BGVs should not negatively affect the survivability of nuclear forces. However, BGVs increase inadvertent escalation risks due to their target ambiguity during flight and by limiting the dual confirmation of a detected launch through radar and heat signatures. Therefore, one key recommendation is that risk-reduction measures should aim at decreasing declaratory ambiguity and diffusing worst-case assumptions.