Only two prototypes were built before the program was cancelled in favor of the turboprop powered Tupolev Tu-95 bomber which could cover the same range at a far higher speed.
Neither the Tu-4 nor the Tu-80 were true intercontinental strategic bombers as they both lacked the range to attack the United States from bases in the Soviet Union and return.
The Tu-85 was designed to achieve the necessary range by use of more powerful and fuel-efficient engines, a redesigned wing to increase the lift/drag ratio and the addition of more fuel.
[2] Actual design work began in August 1948 and was ratified by a directive from the Council of Ministers dated 16 September that required the first prototype to be ready for manufacturer's tests in December 1950.
[3] The second prototype, sometimes referred to as the 85D (dooblyor) or 85/2, incorporated the lessons learned from the first aircraft, including revision and reinforcement of the airframe and a variety of changes to its equipment and systems.