The SS-N-3A SHADDOCK (P-6/ 4K88) is a supersonic Surface-to-Surface anti-ship missile that entered service in the early 1960's. It is powered by a turbojet with launch rocket booster. It has an inertial guidance with mid-course correction via data link and terminal active radar in conventional-armed versions. It carried a nuclear warhead, and was designed to engage US aircraft carriers and their strike groups. The SHADDOCK used programmable midcourse cruise profiles, at altitudes of 1300 ft., 13000 ft. or 23000 ft. AMSL, with radar guided terminal phase at an altitude of around 300 ft. AMSL. The SHADDOCK used a complex guidance scheme, relying on datalink support during the midcourse profile, with the cruise altitude determined largely by the need to maintain line of sight to the launch vessel. After launch the Shaddock would climb to cruise altitude following datalink steering commands, with the missile�s position tracked using a beacon transponder by the FRONT DOOR/FRONT PIECE radars (SSG/SSGN) or SCOOP PAIR (DDG/FFG). Once the Shaddock had line of sight to the target, a video datalink was engaged which relayed the seeker image to an operator on the launch vessel, who would use the datalink to lock the seeker on that target. The missile would then transition to terminal homing and descend to impact, losing datalink contact as it fell below the radio horizon. Because of the datalink, the lowest altitude midcourse profile reduced range to around 55 nautical miles. The P-6 Submarine-deployed Version of the P-35 were deployed on Echo SSGN and Juliet SSGs required the submarines to surface before firing for up to 30 or more minutes until the Shaddock seekers lit up, a major vulnerability. The heavy dependence on datalinks also provided opportunities for jamming. Modes for attacking coastal targets were included.

Note on Nomenclature: The nomenclature of the "SHADDOCK/SEPAL" missile shows the confusion in Western intelligence in the 1960. Both are virtually identical missiles. Further confusing the issue, the earlier variant, the P-5 was given the NATO designator SS-N-3C Shaddock, while the subsequent P-35 versions were designated SS-N-3A and SS-N-3B.

Source: http://www.ausairpower.net/APA-Rus-Cruise-Missiles.html#mozTocId742062; http://www.globalsecurity.org/military/world/russia/ss-n-3.htm; http://www.fas.org/nuke/guide/russia/theater/ss-n-3.htm; http://en.wikipedia.org/wiki/P-5_Pyatyorka