The Pioner UTTKh IRBM was given the expanded mission of
destruction of every enemy rocket launcher in Europe and China,
plus the destruction of key enemy facilities such as air and
naval bases and control bunkers. The original Pioner could only
dispense its multiple warheads to a limited degree, since it
used the warhead dispenser designed for the much longer-range
Temp-2S ICBM. Therefore an improved version was planned. This
would use greater-diameter motors to increase payload, and a new
equipment section and MIRV bus to hit widely-spaced targets with
a single missile. The missile would also have longer range,
allowing it to be based nearly anywhere in the Soviet Union and
still hit targets on the periphery of the Eurasian land mass.
The decree to proceed with development was issued on 19 July
1977. A flight trials series of ten launches was conducted at
Kapustin Yar from 10 August 1979 to 14 August 1980. The missile
was accepted by the military on 23 April 1981. The first
regiment was activated at Yurya in