Armoured warfare
In the early 1960s this led to a number of important developments in the armoured forces and their supporting Arms. One important development was the transition of the Second World War use of Cavalry-Mechanised Group (CMG) into the Cold War Operational Manoeuvre Group (OMG) that was designed to exploit breakthroughs to penetrate NATO's defences in depth. This was a culmination of the Deep Battle theory dating to the 1930s.
In 1964 a significant breakthrough in tank design was achieved in the Soviet Union when the T-64 was produced which for the first time used an automatic loader, reducing the crew of the tank to three crewmen. Subsequently, this model, and the later T-72 and T-80 tanks introduced further innovations that influenced armoured warfare by introducing guided missiles into the tank ammunition mix, allowing ATGW fire from standard tank guns. The Soviet Union was also one of the countries that used two Main Battle Tanks: The high-quality T-80s and lower quality T-72s. Modern Soviet tanks, like the ones mentioned, are typically armed with 125 mm (5 in) smooth bore guns. Advancements in Soviet tanks include improved Fire Control Systems, strong armour protected by ERA, and defensive countermeasures (such as Shtora-1 and Arena). The most advanced Soviet tank, up until the end of the Cold War, was the T-80U, which shared similar characteristics with the M1A1(Turbine engine, advanced Fire Control Systems, strong armour, and firepower)
Infantry fighting vehicles were first developed in the 1960s with the Soviet Union's BMP-1, for the first time allowing supporting infantry to accompany tanks on a battlefield when nuclear weapon use was expected.
The T-64s and BMP-1s were also joined by the self-propelled guns and more importantly Mi-24 Rotary-wing aircraft capable of firing anti-tank missiles entering production in 1970 which were built and theorised as "flying tanks".
The Soviet tank troops, as they were known in the USSR, included armoured units, armoured training regiments and other formations and units.

Vietnam War: M113 armoured personnel carriers proved effective in the terrain of Vietnam against enemy forces which, until 1968, rarely deployed their armour. Though they were soon countered with mines and RPGs, M-113's continued service during the war, primarily evolving into infantry fighting vehicles, known as the ACAV (Armoured Cavalry Assault Vehicle); and functioning as a "light tank."
More heavily armed infantry fighting vehicles such as the M2/M3 Bradley Fighting Vehicle would be based on experience with the M113. Gun trucks were also introduced as M35 trucks fitted with armour and guns to protect convoys. In 1968, Communist forces primarily deployed the Soviet built PT-76 light tank.
By 1971, the larger T-54 medium tanks were fielded, proving themselves susceptible to the M-72 LAW rocket, ARVN M41 Walker Bulldog light tanks, as well as the larger M48A3 Pattons. In January 1969, U.S. armoured cavalry units began exchanging their M48A3 Patton tanks for the M551 Sheridan Armoured Airborne Reconnaissance Assault Vehicles; by 1970 over 200 Sheridan tanks were operating in Vietnam.

21st century: Tanks rarely work alone; the usual minimum unit size is a platoon (a platoon is the smallest U.S. Army/Marine unit led by an officer, and a component of a company or troop) of three to five tanks. The tanks of the platoon work together providing mutual support: two might advance while covered by the others then stop and provide cover for the remainder to move ahead.
Normally, multiple platoons coordinate with mechanised infantry and use their mobility and firepower to penetrate weak points in enemy lines. This is where the powerful engines, tracks and turrets come into play. The ability to rotate the turret by a full 360° allows coordinated movement within and between platoons, while defending against attacks from multiple directions and engaging troops and vehicles without stopping or slowing down.
When on the defensive, they wait in prepared positions or use any natural terrain elements (such as small hills) for cover. A tank sitting just behind a hill crest ("hull-down") exposes only the top of its turret, with the gun and sensors, to the enemy, leaving the smallest possible target while allowing it to engage the enemy on the other side of the hill. Tanks are usually able to depress the main gun below the horizontal since modern kinetic energy (KE) rounds have nearly flat trajectories. Without this they would be unable to exploit such positions. However, upon cresting a hill, the tank may expose its thinly armoured underside to enemy weapons.
The disposition of armour around a tank is not uniform; the front is typically better armoured than the sides or rear. Accordingly, normal practice is to keep the front towards the enemy at all times; the tank retreats by reversing instead of turning around. Driving backwards away from an enemy is even safer than driving forwards towards them since driving forwards over a bump can throw the front of the tank up in the air, exposing the thin armour of the underside and taking the gun off the target due to its limited angle of depression.
The tracks, wheels and suspension of a tank are outside the armoured hull and are some of the most vulnerable spots. The easiest way to disable a tank (other than a direct hit in a vulnerable area with a full-power anti-tank weapon) is to target the tracks for a "mobility kill" (m-kill), or target all external visual aids with rubbery cohesive substances such as melted rubber or blackened high viscosity epoxy resins. Once a tank is disabled it is easier to destroy. This is why side-skirts are an important feature; they can deflect heavy machine-gun bullets and trigger the detonation of high-explosive anti-tank (HEAT) rounds before they strike the running gear. Other vulnerable parts of a typical tank include the engine deck (with air intakes, radiators, etc.) and the turret ring, where the turret joins the hull.
When used defensively, tanks are often sunk into trenches or placed behind earth berms for increased protection. The tanks can fire off a few shots from their defensive position, then retreat (reversing) to another prepared position further back and drive behind the berms or into the trenches there. These positions can be constructed by the tank crews, but preparations are better and quicker if carried out by combat engineers with bulldozers. Overhead protection, even if it is fairly thin, can also be very useful since it can help pre-detonate artillery shells and avoid direct hits from above which can be deadly to tanks, by striking them at their thinnest armour. In short, tank crews find as many ways as possible to augment the armour on their vehicles.
Tanks usually go into battle with a round in the gun, ready to fire, to minimise reaction time when encountering an enemy. The US doctrine calls for this round to be a kinetic energy (KE) round, as the reaction time is most important when meeting enemy tanks, to get the first shot (and possibly the first kill). If troops or light vehicles are encountered, the usual response is to fire this round at them, despite it not being ideal—it is difficult and time-consuming to remove a round which is already in the breech. In this case, after the KE round is fired, a HEAT round would normally be loaded next to continue the engagement.
Tanks can be decisive in city fighting, with the ability to demolish walls and fire medium and heavy machine guns in several directions simultaneously. However, tanks are especially vulnerable in urban combat. It is much easier for enemy infantry to sneak up behind a tank or fire at its sides, where it is most vulnerable. In addition, firing down from multi-story buildings allows shots at the thin upper turret armour and even basic weapons like Molotov cocktails, if aimed at the engine air intakes, can disable a tank. Because of these limits, tanks are difficult to use in city conflicts where civilians or friendly forces might be nearby, since their firepower can't be used effectively.
Some analysts argue that recent conflicts, like the Russian invasion of Ukraine, highlight the growing vulnerability of tanks. Estimates from early 2024 indicate that Russia has lost around 3,000 tanks in the first two years of the conflict, with the actual number likely being higher. In contrast, during the Israel-Hamas war, Israeli tanks equipped with active protection systems (APS) showed improved survivability against anti-tank missiles. Additionally, using tanks in pairs with overlapping APS provided extra defense and enhanced their overall effectiveness.

Airborne threats: Tanks and other armoured vehicles are vulnerable to attack from the air for several reasons. One is that they are easily detectable—the metal they are made of shows up well on radar, and is especially obvious if they are moving in formation. A moving tank also produces a lot of heat, noise and dust. The heat makes seeing them on a forward-looking infra-red system easy and the dust is a good visual cue during the day.
The other major reason is that most armoured vehicles have thinner armour on the roof of the turret and on the engine deck, so an anti-tank guided missile or bomb (from an attack helicopter, unmanned combat aerial vehicle, ground-attack jet or small drone) hitting them from the top can be deadly even if it has a small warhead. Even a small automatic cannon is powerful enough to penetrate the rear and top sections of the engine compartment of a tank.