By the early 1950s the Army was firmly established in the surface-to-air missile field with their Nike and Nike B missile projects.
These projects had been led by Bell Labs, working with Douglas.

The Army contacted the Johns Hopkins University Operations Research Office (ORO) to consider the task of shooting down ballistic missiles using a Nike-like system.
The ORO report took three years to complete, and the resulting The Defense of the United States Against Aircraft and Missiles was comprehensive.
While this study was still progressing, in February 1955 the Army began initial talks with Bell, and in March they contracted Bell's Nike team to begin a detailed 18-month study of the problem under the name Nike II.

The first section of the Bell study was returned to the Army Ordnance department at the Redstone Arsenal on 2 December 1955.
It considered the full range of threats including existing jet aircraft, future ramjet powered aircraft flying at up to 3,000 knots (5,600 km/h), short-range ballistic missiles of the V-2 type flying at about the same speed, and an ICBM reentry vehicle (RV) traveling at 14,000 knots (26,000 km/h).
They suggested that a missile with a common rocket booster could serve all of these roles by changing between two upper stages; one with fins for use in the atmosphere against aircraft, and another with vestigial fins and thrust vectoring for use above the atmosphere against missiles.

Considering the ICBM problem, the study went on to suggest that the system would have to be effective between 95 and 100% of the time in order to be worthwhile.
They considered attacks against the RV while the missile was in the midcourse, just as it reached the highest point in its trajectory and was traveling at its slowest speed.
Practical limitations eliminated this possibility, as it required the ABM to be launched at about the same time as the ICBM in order to meet in the middle, and they could not imagine a way to arrange this.
Working at much shorter ranges, during the terminal phase, seemed the only possible solution.

Bell returned a further study, delivered on 4 January 1956, that demonstrated the need to intercept the incoming warheads at 100-mile (160 km) altitude, and suggested that this was within the abilities of an upgraded version of the Nike B missile.
Given a terminal speed up to 5 miles per second (18,000 miles per hour (29,000 km/h)), combined with the time it would take an interceptor missile to climb to the RV's altitude, the system required that the RV be initially detected at about 1,000 miles (1,600 km) range.
Due to the RV's relatively small size and limited radar signature, this would demand extremely powerful radars.

To ensure the destruction of the RV, or at least render the warhead within it unusable, the W31 would have to be fired when it was within a few hundred feet of the RV.
Given the angular resolution of existing radars, this limited the maximum effective range significantly.
Bell considered an active radar seeker, which improved accuracy as it flew toward the RV, but these proved too large to be practical.
 A command guidance system like the early Nike systems seemed to be the only solution.

The interceptor would lose maneuverability as it climbed out of the atmosphere and its aerodynamic surfaces became less effective, so it would have to be directed onto the target as rapidly as possible, leaving only minor fine-tuning later in the engagement.
This required that accurate tracks be developed for both the warhead and outgoing missile very quickly in comparison to a system like Nike B where the guidance could be updated throughout the engagement.
This, in turn, demanded new computers and tracking radars with much higher processing rates than the systems used on earlier Nikes.
Bell suggested that the recently introduced transistor offered the solution to the data processing problem.

After running 50,000 simulated intercepts on analog computers, Bell returned a final report on the concept in October 1956, indicating that the system was within the state of the art.
A 13 November 195
By the early 1950s the Army was firmly established in the surface-to-air missile field with their Nike and Nike B missile projects. These projects had been led by Bell Labs, working with Douglas.
The Army contacted the Johns Hopkins University Operations Research Office (ORO) to consider the task of shooting down ballistic missiles using a Nike-like system. The ORO report took three years to complete, and the resulting The Defense of the United States Against Aircraft and Missiles was comprehensive. While this study was still progressing, in February 1955 the Army began initial talks with Bell, and in March they contracted Bell's Nike team to begin a detailed 18-month study of the problem under the name Nike II.
The first section of the Bell study was returned to the Army Ordnance department at the Redstone Arsenal on 2 December 1955. It considered the full range of threats including existing jet aircraft, future ramjet powered aircraft flying at up to 3,000 knots (5,600 km/h), short-range ballistic missiles of the V-2 type flying at about the same speed, and an ICBM reentry vehicle (RV) traveling at 14,000 knots (26,000 km/h). They suggested that a missile with a common rocket booster could serve all of these roles by changing between two upper stages; one with fins for use in the atmosphere against aircraft, and another with vestigial fins and thrust vectoring for use above the atmosphere against missiles.
Considering the ICBM problem, the study went on to suggest that the system would have to be effective between 95 and 100% of the time in order to be worthwhile. They considered attacks against the RV while the missile was in the midcourse, just as it reached the highest point in its trajectory and was traveling at its slowest speed. Practical limitations eliminated this possibility, as it required the ABM to be launched at about the same time as the ICBM in order to meet in the middle, and they could not imagine a way to arrange this. Working at much shorter ranges, during the terminal phase, seemed the only possible solution.
Bell returned a further study, delivered on 4 January 1956, that demonstrated the need to intercept the incoming warheads at 100-mile (160 km) altitude, and suggested that this was within the abilities of an upgraded version of the Nike B missile. Given a terminal speed up to 5 miles per second (18,000 miles per hour (29,000 km/h)), combined with the time it would take an interceptor missile to climb to the RV's altitude, the system required that the RV be initially detected at about 1,000 miles (1,600 km) range. Due to the RV's relatively small size and limited radar signature, this would demand extremely powerful radars.
To ensure the destruction of the RV, or at least render the warhead within it unusable, the W31 would have to be fired when it was within a few hundred feet of the RV. Given the angular resolution of existing radars, this limited the maximum effective range significantly. Bell considered an active radar seeker, which improved accuracy as it flew toward the RV, but these proved too large to be practical.  A command guidance system like the early Nike systems seemed to be the only solution.
The interceptor would lose maneuverability as it climbed out of the atmosphere and its aerodynamic surfaces became less effective, so it would have to be directed onto the target as rapidly as possible, leaving only minor fine-tuning later in the engagement. This required that accurate tracks be developed for both the warhead and outgoing missile very quickly in comparison to a system like Nike B where the guidance could be updated throughout the engagement. This, in turn, demanded new computers and tracking radars with much higher processing rates than the systems used on earlier Nikes. Bell suggested that the recently introduced transistor offered the solution to the data processing problem.
After running 50,000 simulated intercepts on analog computers, Bell returned a final report on the concept in October 1956, indicating that the system was within the state of the art. A 13 November 195
Nike Zeus