Defence sys

• Patriot, e.g. (abbr.)
• SALT subject, for short
• Air defence sys
• Defense syst.
• Counter-missile: Abbr.
• Anti missile missile (abbr.)
• Modern def. weapon
• Missile abbr
• Def. projectile

Douglas Harper's Etymology Dictionary Word definitions in Douglas Harper's Etymology Dictionary
1963, initialism (acronym) for anti-ballistic missile.