Sergeant Ryhter was a member of Battery A, 82nd Anti-Aircraft Artillery (Automatic Weapons) Battalion, 2nd Infantry Division. He was listed as Missing in Action while fighting the enemy near Kunu-ri, North Korea on December 1, 1950. He was presumed dead on December 31, 1953. His name is inscribed on the Courts of the Missing at the Honolulu Memorial.

Through the work of the Defense POW/MIA Accounting Agency, the remains of Sergeant John P. Ryhter were accounted for in 2024. His name is permanently inscribed on the “Courts of the Missing” at the Honolulu Memorial.