Panzerjäger and Jagdpanzer vehicles—and the Samokhodnaya ustanovka families of AFV's for the Soviets: such turretless, casemate-style tank destroyers and assault guns were less complex, stripped down tanks carrying heavy guns, solely firing forward. The firepower and low cost of these vehicles made them attractive but as manufacturing techniques improved and larger turret rings made larger tank guns feasible, the gun turret was recognized as the most effective mounting for the main gun to allow movement in a different direction from firing, enhancing tactical flexibility. Cold War During the Cold War, tension between the Warsaw Pact countries and North Atlantic Treaty Organization (NATO) countries created an arms race that ensured that tank development proceeded largely as it had during World War II. The essence of tank designs during the Cold War had been hammered out in the closing stages of World War II. Large turrets, capable suspension systems, greatly improved engines, sloped armour and large-caliber (90 mm and larger) guns were standard. Tank design during the Cold War built on this foundation and included improvements to fire control, gyroscopic gun stabilization, communications (primarily radio) and crew comfort and saw the introduction of laser rangefinders and infrared night vision equipment. armour technology progressed in an ongoing race against improvements in anti-tank weapons, especially antitank guided missiles like the TOW. Medium tanks of World War II evolved into the main battle tank (MBT) of the Cold War and took over the majority of tank roles on the battlefield. This gradual transition occurred in the 1950s and 1960s due to anti-tank guided missiles, sabot ammunition and high-explosive anti-tank warheads. World War II had shown that the speed of a light tank was no substitute for armour & firepower and medium tanks were vulnerable to newer weapon technology, rendering them obsolete. In a trend started in World War II, economies of scale led to serial production of progressively upgraded models of all major tanks during the Cold War. For the same reason many upgraded post-World War II tanks and their derivatives (for example, the T-55 and T-72) remain in active service around the world, and even an obsolete tank may be the most formidable weapon on battlefields in many parts of the world. Among the tanks of the 1950s were the British Centurion and Soviet T-54/55 in service from 1946, and the US M48 from 1951. These three vehicles formed the bulk of the armoured