| R |
| R | Refrigerated Rations |
| R&D | Research and Development |
| R&I | Recognition/Indentification |
| R&I | Recruitment and Induction |
| R&R | Repair & Return |
| R&R | Rest and Recuperation |
| R. AND A. | Review and Analysis Branch |
| R.P. | Republic of the Philippines |
| RAA | Royal Australian Army |
| RAAF | Royal Australian Air Force |
| RAC | Reconnaissance Airplane Company |
| RAC | Regional Assistance Command |
| RAC | Research Analysis Corporation |
| RAC | River Assault Craft |
| RAD | Reports and Analysis Division (CORDS) |
| RAD | Research and Analysis Directorate, CORDS |
| RAD | River Assault Division |
| RADM | Rear Admiral |
| RADS | Rapid Area Distribution Support |
| RAG | Replacement Air Group |
| RAG | River Assault Group |
| RAID | River Assault and Interdiction Division |
| Rallier | Chieu Hoi Returnee |
| RAM | Rapid Area Maintenance |
| RAMMS | RVNAF Automated Materiel Management System |
| RAN | Royal Australian Navy |
| RAND | Research and Development Corporation |
| RAR | Royal Australian Regiment |
| RAS | River Assault Squadron |
| RATS | Remote Area Terminal System |
| RAV | Restricted Availability |
| RAW | MAP Automated Material Management System |
| RB | Refuel Barge |
| RBD | Ranger Border Defense |
| RBDB | Ranger Border Defense Battalion |
| RBE | Red Ball Express |
| RC | Reserve Constabulary |
| RC | Revolutionary Committee |
| RC | Rural Construction |
| RC-47 | Reconnaissance C-47 |
| RCA | Riot Control Agent |
| RCAT | Regimental Combat Assistance Team |
| RCC | Rescue Coordination Center |
| RCC | Rural Construction Cadre |
| RCDC | Radar Course Directory Central |
| RCG | Rural Construction Group |
| RCMOD | Reconnaissance Modification |
| RCN | Reference Control Number |
| RCO | Representative Contracting Officer |
| RCP | Rural Construction Program |
| RCT | Regimental Combat Team |
| RD | Revolutionary Development |
| RD | Rural (formerly Revolutionary) Development |
| Rd(s) | Round(s) |
| RDC | Revolutionary Development Cadre |
| RDC | Rural (formerly Revolutionary) Development Cadre |
| RDD | Required Delivery Date |
| RDFU | Research and Development Field Unit |
| RDMTT | Revolutionary Development Mobile Training Teams |
| RDPG | Revolutionary Development People's Group |
| RDPG | Rural (formerly Revolutionary) Development People's Group |
| RDS | Rounds |
| RDSD | Rural (formerly Revolutionary) Development Support Directorate |
| RDT&E | Research, Development, Testing and Evaluation |
| RDV | Requisition Dollar Value |
| RDW | Rural (formerly Revolutionary) Development Workers |
| Ready light | Light which indicates a particular avionics/munitions system is operating and available for use. |
| REC | Receive |
| RECAT | Redeployment Base Closure Assistance Team |
| RECCE | Reconnaissance |
| Recon/RECON | Reconnaissance |
| RED CROWN | Voice call for USS LONG BEACH (CLN-9) |
| RED HORSE | Rapid Engineering Deployment and Heavy Operational Repair Squadrons, Engineering Regiment. |
| REDCON | Readiness Condition |
| REFCOTT | Regional Forces Company Training Team |
| Regional Forces | Provincial armed forces known previously as the Civil Guard (Bao An). |
| Regt/REGT | Regiment |
| REGTL | Regimental |
| Regular Forces | The Arry, Navy, and Air Force of Vietnam. |
| REINF | Reinforced |
| Release agreement | Vietnamese-American agreements funding province-level rehabilitation programs. |
| REMAN | Resource Management |
| REP | Representative |
| RESCAP | Rescue Combat Air Patrol |
| RESP | Responsibility |
| RESP | Rural Elementary School Program |
| Responsible Cohesion | The social condition that exists when institutions have achieved a degree of success in coping with problems that is acceptable to society members. |
| RET | Returned |
| Revolutionary Development Cadres | The name given by the American Mission to what the Vietnamese call Rural Construction cadre. Also referred to as Rural Reconstruction Cadre. |
| RF | Radio Frequency |
| RF | Regional Force (RVNAF) |
| RF MG | Regional Force Mobile Group |
| RF-5 | Reconnaissance F-5 |
| RF/PF | Regional Forces/Popular Forces |
| RFCOTT | Regional Force Company Training Teams |
| RFI | Radio Frequency Interference |
| RFTC | Regional Force Training Center |
| RGNU | Royal Government of National Union |
| Rgr/RGR | Ranger |
| RHAW | Radar Homing and Warning |
| RID | River Interdiction Division |
| RIF | Reduction in Force |
| RIMMS | RVNAF Improvement and Modernization Management System |
| RIO | Radar Intercept Officer |
| RIVASRON | River Assault Squadron |
| RIVDIV | River Assault Division |
| RIVFLOTONE | River Flotilla One |
| RIVRON | River Squadron |
| RKG | Royal Khmer (Cambodia) Government |
| Rkt | Rocket |
| RL | Rocket Launcher |
| RLA | Royal Laotian Army |
| RLAF | Royal Laotian Air Force |
| RLF | Royal Laotian Forces |
| RLG | Royal Lao Government |
| RLOW | Radar Lock on Warning |
| RLT | Regimental Landing Team |
| RMK | Raymond Morrison-Knudsen |
| RMK-BRJ | Raymond-Morrison-Knudsen /Brown-Root-James (Civilian Construction Firm) |
| RNZ | Royal New Zealand |
| RNZAF | Royal New Zealand Air Force |
| RO | Abbreviated form of Radio Intercept Officer. |
| RO | Requisitioning Objective/Requirement Objective |
| Road interdiction | To prevent or hinder, by aerial means, enemy use of a road or route. |
| ROC | Republic of China |
| ROCMAAGV | Republic of China Military Assistance Advisory Group Vietnam |
| ROCMAGV | Republic of China Military Assistance Group, Vietnam |
| ROE | Rules of Engagement |
| ROH | Regular Overhaul |
| ROI | Report/Results of Investigation |
| ROK | Republic of Korea |
| ROKA | Republic of Korea Army |
| ROKAF | Republic of Korea Air Force |
| ROKAF(V) | Republic of Korea Air Force (Vietnam) |
| ROKFV | Republic of Korea Forces, Vietnam |
| ROKG | Republic of Korea Government |
| ROKMACV | Republic of Korea, Military Assistance Command, Vietnam |
| ROKMAGV | Republic of Korea Military Assistance Group, Vietnam |
| ROKMC | Republic of Korea Marine Corps |
| ROKN | Republic of Korea Navy |
| ROl | Report of Investigation |
| ROLLING THUNDER | Code name for air strikes against North Vietnam. |
| ROP | Republic of the Philippines |
| Route Package | Geographical division of North Vietnam for purposes of air strike targeting. |
| RP | Route Package |
| RPC | Reparable Processing Center |
| RPC | River Patrol Craft |
| RPD | River Patrol Division |
| RPDC | Regional Pacification and Development Council(s) |
| RPG | River Patrol Group |
| RPG | Rocket-Propelled Grenade |
| RPIE | Real Property Installed Equipaent |
| RR | Rail Road |
| RR | Recoilless Rifle |
| RRU | Radio Research Unit |
| RSG | Rear Service Group |
| RSR | Required Supply Rate |
| RSSZ | Rung Sat Special Zone |
| RT | ROLLING THUNDER |
| RT | Route |
| RTA | Royal Thai Army |
| RTAF | Royal Thai Air Force |
| RTAFB | Royal Thai Air Force Base |
| RTAFCONV | Royal Thai Air Force Contingent Vietnam |
| RTAFV | Royal Thai Army Volunteer Force |
| RTAVF | Royal Thai Army Vietnam Forces |
| RTAVR | Royal Thai Army Volunteer/Vietnam Regiment |
| RTEG | River Transport Escort Group |
| RTF | Reconnaissance Task Force |
| RTFV | Royal Thai Forces, Vietnam |
| RTFVN | Royal Thai Forces, Vietnam |
| RTG | Royal Thai Government |
| RTMAGV | Royal Thai Military Assistance Group, Vietnam |
| RTN | Royal Thai Navy |
| RTO | Radio Telephone Operator |
| RTTL | ROLLING THUNDER Target List |
| RTV | Return to Village |
| RUDD | Remote Underwater Detection Device |
| Rudder reversal | Climbing aircraft maneuver in which direction is changed by rotation around the aircraft's vertical axis. |
| Rural Construction | Rural Construction encompasses all civilian, military and police actions to eliminate organized VC military activity; to detect and eliminate the overt and covert VC political apparatus. |
| Rural Construction Cadres | A fusion of all rural pacification cadre systems in late 1965. Often called Rural Reconstruction Cadres, Political Action Teams (PAT), and Revolutionary Development Cadres. |
| RUWSTAF | Rural Water Supply Task Force |
| RVN | Republic of (South) Vietnam |
| RVN-CCU | Republic of Vietnam-Contingency Communications Unit |
| RVNAF | Republic of Vietnam Armed Forces |
| RVNAFLS | Republic of Vietnam Armed Forces Language School |
| RVNR | Vietnam Regional Exchange |
| RWD | Rounds Per Weapon Per Day |
| RYM | Republican Youth Movement |