The Vietnamese Rangers, properly known in Vietnamese as the Biệt Động Quân (En:Commando) and commonly known as the ARVN Rangers, were the light infantry of the Army of the Republic of Vietnam. Trained and assisted by American Special Forces and Ranger advisers, the Vietnamese Rangers infiltrated beyond enemy lines in search and destroy missions. Initially trained as a counter-insurgency light infantry force by removing the fourth company each of the existing infantry battalions, they later expanded into a swing force capable of conventional as well as counter-insurgency operations, and were relied on to retake captured regions.