600 Pattons would be deployed with US Forces during the war. The initial M48s landed with the US Marines in 1965. The remaining Pattons deployed to South Vietnam were in three U.S. Army battalions: the 177th Armor near the DMZ, the 169th Armor in the Central Highlands, and the 234th Armor near the Mekong Delta. Each battalion consisted of approximately fifty seven tanks. M48s were also used by Armored Cavalry Squadrons in Vietnam, until replaced by M551 Sheridan tanks. The M67A1 flamethrower tank (nicknamed the Zippo) was an M48 variant also used in the conflict. When US forces commenced redeployment operations, many of the M48A3 Pattons were turned over to the Army of the Republic of Vietnam (ARVN) forces, in particular creating the ARVN 20th Tank Regiment, which supplemented their M41 Walker Bulldog units. During the North Vietnamese Army (NVA) Easter Offensive in 1972, tank clashes between NVA T-54/PT-76 and ARVN M48/M41 units became commonplace, but on 23 April 1972, tankers of the 20th Tank Regiment were attacked by an NVA infantry-tank team, which was equipped with the new 9M14M Malyutka (NATO designation: Sagger) wire guided anti-tank missile. During this battle, one M48A3 Patton tank and one M113 Armored Cavalry Assault Vehicle (ACAV) were destroyed, becoming the first losses to the Sagger missile; losses that would echo on an even larger scale a year later during the Yom Kippur War in the Middle East in 1973. The M48s performed admirably in Vietnam in the infantry-support role. However, there were few actual tank versus tank battles. The M48s provided adequate protection for its crew from small arms, mines, and rocket-propelled grenades. In the mid-1970s, the M48A5 upgrade was developed to allow the vehicle to carry a heavier 105 mm gun. This was designed to bring the M48s up to standard with the M60 tanks then in regular use. Most of the M48s were placed into service with reserve units by this time. By the mid-1990s, all M48s were phased out. Main battle tanks M60 The M60 tank was designed as a replacement for the M48 Patton and is based on a modified M48 hull. In 1957, plans were laid in the US for a tank with a 105 mm main gun and a redesigned hull, offering better armor protection. The resulting M60 largely resembled the M48 it was based on, but has significant differences: the M60 mounted a bore evacuated 105