In some cases, there are also single sources for key components and sub-components.

The Javelin, for instance, relies on a rocket motor—the Aerojet Rocketdyne’s advance solid-propellant rocket motor—without a second source at the moment. There is one company, Williams International, that builds turbofan engines for most cruise missiles, such as the Joint Air-to-Surface Standoff Missile, Joint Air-to-Surface Standoff Missile-Extended Range, and Long-Range Anti-Ship Missile. There is one main company, PacSci EMC, that produces the energetics for most missiles. There is also one foundry that can produce the large titanium castings for some important weapons systems.