A graphic depicting a notional common Terminal Stage Interceptor (TSI) for use across all variations of the Naval Modular Missile (NMM). A 21-inch rocket motor is a key component of the Standard Missile-3 Block IIA anti-ballistic missile interceptors in Navy inventory today. Historically, the most immediate use case for a submarine-launched anti-air missile capability has been localized defense against anti-submarine aircraft and helicopters, as seen in the video below. VPM tubes are designed to accommodate a variety of munitions, including Tomahawk land-attack cruise missiles and Intermediate-Range Conventional Prompt Strike (IRCPS) hypersonic missiles. General Dynamics Electric BoatIn the missile defense context, the submarine with mid-course ballistic missile and/or hypersonic missile interceptors onboard could provide a more forward launch point for midcourse interception of these weapons.