SOKS, or Systemа Obnarujenia Kilvaternogo Sleda (, "wake object detection system"), is a non acoustic

submarine detection system Submarine detection systems are an aspect of antisubmarine warfare. They are of particular importance in nuclear deterrence, as they directly undermine one of the three arms of the nuclear triad by making counter-force attacks on submarines possib ...

created by the

Soviet Union The Union of Soviet Socialist Republics. (USSR), commonly known as the Soviet Union, was a List of former transcontinental countries#Since 1700, transcontinental country that spanned much of Eurasia from 1922 until Dissolution of the Soviet ...

. SOKS functions by detecting

radionuclides A radionuclide (radioactive nuclide, radioisotope or radioactive isotope) is a nuclide that has excess numbers of either neutrons or protons, giving it excess nuclear energy, and making it unstable. This excess energy can be used in one of three ...

from the nuclear reactor in submarines, chemical signatures, and changes in the

refractive index In optics, the refractive index (or refraction index) of an optical medium is the ratio of the apparent speed of light in the air or vacuum to the speed in the medium. The refractive index determines how much the path of light is bent, or refrac ...

of water in the wake of submarines. It was first installed on the ''November''-class K-14 submarine in 1969. SOKS was revealed in a 1972 document written by the

Central Intelligence Agency Directorate of Science & Technology The Directorate of Science & Technology (DS&T) is the branch of the United States Central Intelligence Agency (CIA) tasked with collecting and analyzing information through technological means and developing technical systems to advance the CIA's ...

and declassified in June 2017.

References

{{reflist Anti-submarine warfare Submarine detection systems Soviet inventions