After the end of WW2, the German scientists who developed the V-2 ballistic missile together with associated technical equipment/documentation were split between the United States and the Soviet Union.
These countries developed two parallel 'recruitment' schemes.
The US scheme was named 'Operation Paperclip' and they obtained the services of the major scientists (including Wehrner von Braun) and full documentation.
They also captured a significant amount of hardware at the Nordhausen production facility.
Some of the 1,600 German rocket scientists and technicians who moved to work in the United States
The Soviet Union scheme was named 'Operation Osoaviakhim'.
On the 22nd October 1946, Soviet army units, at gunpoint, 'recruited' more than 2,200 German specialists from the Soviet occupation zone of post-war Germany – a total of more than 6,000 people including family members.
There were few major scientists in this group and they were unable to discover full documention.
However, the Soviet occupied area included the former research centre at Peenemünde.
Technical equipment, the scientists, their families and their possessions were sent to the Soviet Union
Given the background of the scientists, it is no surprise that the two programmes produced similar missiles.
In the Soviet Union, the R-1 missile was developed from the German V-2 design.
The Soviet R-2 missile (an improved R-1 design) had a warhead which separated from the rocket prior to atmospheric re-entry.
This eliminated the hull strength problem, one of the V-2/R-1's biggest weaknesses - they broke up on re-entry.
A Soviet R-1, a German V-2, a US Redstone missile and a Soviet R-2