The 1S12 (also referred to by the NATO reporting name "Long Track" in the west) is a 3-D UHF radardeveloped and operated by the former Soviet Union.

The P-40 started development in 1960 and by 1962 the radar had completed state trials and in 1963 was accepted into service by the anti-aircraft troops of the Soviet armed forces.

   In 1965 the P-40 gained the GRAU designation 1S12 as it was adopted as the target acquisition radar of the 2K11 Krug mobile anti-aircraft defence system. The main difference between P-40 and 1S12 is the additional "Telecode system" 1S62, with an telescope antenna at front right of chassis, to share datas between 1S12 and 1S32.

   Between the 1966 and 1968 the radar was upgraded, increasing the range of the system. Later, between 1969 and 1970, the radar's range was again improved in addition to achieving better reliability.