“... deployed 44 ground-based interceptors, or GBIs: 40 at Fort Greeley, Alaska, and four at Vandenberg Air Force Base, California. If deterrence fails, those interceptors would be the last line of defense against a North Korean missile. Each incoming ICBM might be met with four or more GBIs.”
48/4=12. Book title: “The Thirteenth Missile”.
No one in the industry believes that Russia nor China has fielded the ability to shoot one down.