Missles can be launched from aircraft, ships or land. They are referred to as air to air and surface to air missles.

The missiles are pushed out of their silos with compressed air and rise to the surface literally in a bubble of air. Very little seawater comes into contact with the missile until it breaks the surface of the water. The missile is ignited at the surface and the guidance system steers it to it's target.

In 1955 in the US, the ICBM was still generally considered impractical, nuclear warheads were just too large and heavy for them. Work was in progress on IRBMs and SRBMs. Surface to air, air to air, and air to surface missiles with nuclear warheads were already in stockpile as antiaircraft and standoff weapons.