In May 1988, the US Air Force chose General Dynamics (now Lockheed Martin) to develop the Atlas II vehicle, primarily to launch Defense Satellite Communications System payloads under the Medium Launch Vehicle II (MLV-II) program.

[4] Additional commercial and U.S. Government sales resulted in production increases leading to greater than 60 vehicles being produced and launched.

The increased thrust, engine efficiency, and propellant capacity enabled the vehicle to lift payloads of 6,100 pounds (2,767 kg) into geostationary transfer orbit (GTO), or more on later Atlas II variants.

This system, mounted on the interstage between the first and second stages, utilized small thrusters to control the vehicle's roll.

The two RS-56-OBA engines were integrated into a single unit called the MA-5A and shared a common gas generator.

[10][7] The first stage also had the option to be fitted with 4 Castor 4A solid rocket boosters as part of the IIAS version, each providing an additional 478.3 kN (107,500 lbf) of thrust for 56 seconds.

The two stainless steel propellant tanks were separated by a common bulkhead, which helped keep mass down.

The two engines could be fitted with extendable nozzles, which would provide an increase in efficiency and therefore performance.

It was powered by two R-4D engines and could operate on-orbit for up to twelve days before deploying its payload, allowing additional flexibility in mission planning.

Similarly, rockets with Large or Extended fairings suffered slight hits to their payload capacity.

Its lengthened propellant tanks and improved electronics over the Atlas I offered better performance.

It was designed to work as part of the US Air Force's Medium Launch Vehicle II program.