The Atlas ICBM was first deployed, operationally, by the USAF in 1960. It was the second leg of the so-called ‘nuclear triad’. The Strategic Air Command (SAC) bombers were the first and the Navy’s Polaris SLBMs, deployed on nuclear submarines, were the third.

The ‘D’ series Atlas had 360,000 pounds of thrust generated by two booster engines, a sustainer engine and two vernier engines. The boosters jettisoned shortly after blast-off, leaving target attainment (military launches) or orbit injection (civilian and/or research launches) to the sustainer. The verniers provided continuous in-flight course corrections. Max. velocity was ~16,000 mph.

By the time the Atlas was retired from active service in 1965, 129 missiles of the D (30), E (27) and F (72) series had been deployed. In total, 350 Atlas missiles were produced. All deployed Atlas missiles were replaced by the Titan series as the next step in the upgrading of the country’s nuclear deterrent forces. All the Atlases were then utilized in numerous and varied launches for research and national defense/security purposes.

Atlas – first deployed was the SM-65D (coffin-based, radio guidance), later versions were the SM-65E (coffin-based, inertial guidance) and SM65-F (silo-based, inertial guidance). All had liquid-fuel propulsion systems.

Jupiter – US Army Intermediate-Range Ballistic Missile (IRBM)

Polaris – first US Navy Submarine-Launched Ballistic Missile (SLBM)

Titan – USAF’s ‘second generation’ ICBM

More Info: en.wikipedia.org