HistoryData
Historical ConflictKorea

Operation Killer

Operation Killer was the second major UN counter-offensive in the Korean War, designed to destroy enemy forces south of the Arizona Line in early 1951.

Duration & Scope

1951 ongoing

< 1 year

Key Facts

Start date
20 February 1951
End date
6 March 1951
Duration
~14 days
Commanding general
General Matthew Ridgway
Objective line
Arizona Line
Followed by
Operation Ripper

Strategic Narrative Overview

Operation Killer began on 20 February 1951 as UN forces advanced on a broad front across central Korea. Ridgway's plan prioritised attrition of PVA and KPA forces south of the designated Arizona Line. The operation lasted approximately two weeks, with UN units pushing enemy formations northward through difficult winter terrain. It concluded on 6 March 1951 and transitioned immediately into the follow-on Operation Ripper.

01 / The Origins

By early 1951, Chinese People's Volunteer Army and North Korean Army forces had pushed UN Command back below the 38th parallel following massive intervention in late 1950. General Matthew Ridgway, newly in command of the Eighth Army, sought to reverse the situation by launching a series of deliberate counter-offensives aimed at destroying enemy manpower rather than simply seizing territory, reflecting a shift in UN strategy.

03 / The Outcome

Operation Killer succeeded in its stated objective of pressuring and displacing PVA and KPA units south of the Arizona Line. The operation stabilised the UN front and set conditions for Operation Ripper. It marked a broader strategic shift under Ridgway toward attritional warfare and methodical advances rather than deep exploitation, contributing to the eventual stabilisation of the Korean front near the 38th parallel.

Belligerents & Mobilization Analysis

Side A

1 belligerent

United Nations Command
Key Commanders

Matthew Ridgway.

Side B

2 belligerents

Chinese People's Volunteer Army (PVA)North Korean People's Army (KPA)
Outcome
UN victory; PVA and KPA forces pushed north of the Arizona Line; operation immediately followed by Operation Ripper

Location

Map of South KoreaMap of South KoreaSouth Korea