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Interagency Intelligence Report
Prospects for Soviet Success in Improving Detection of Submarines in Open Ocean Areas
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PROSPECTS FOR SOVIET SUCCESS IN IMPROVING DETECTION OF SUBMARINES IN OPEN OCEAN AREAS
PREFACE
This Interagency Intelligence Report was prepared by the Defense Intelligence Agency with the collaboration of the Central Intelligence Agency and the Naval Intelligence Conunand. It was reviewed by the National Security Agency and the Bureau of Intelligence and Research, Department of State.
The report was prepared at the request of tlie National Intelligence Officer for Strategic Programs. It assessesn antisubmarine warfare (ASW) detection techniques and its implications for theof the US nuclear-powered ballistic missile launching(SSBN) force.
The report describes current Soviet ASW detection capabilities and tlteir limitations, examines identified andfforts in ASW, and provides an assessment of the potential for Soviet solution of the open ocean submarine detection problem by acoustic and non-acoustic methods. Information cutoff date of this report is
PROSPECTS FOR SOVIET SUCCESS IN IMPROVING DETECTION OF SUBMARINES IN OPEN OCEAN AREAS
KEY JUDGMENTS
The principal continuing weakness in Soviet ASW is the lackapability to detect submarines at long ranges within the broadof open oceans. Soviet systems for defecting submarines using passive acoustic arrays which are permanently emplaced in the water
^Geographic and technical considerationsmilitate against the useong-range passive .acoustic systemsimilar to the US Sound Surveillance System (SOSUS).
There are indications the Soviets believe that non-acoustichave potential for improving their capabilities in the open ocean. We know thatn non-acoustic detection primarily involves mobile sensors, but we lack information on many aspects of these programs. There is no evidence that the Soviets arc investigating
detectable submarine effects which have not already been considered in the US; however, US investigation of these effects has not, in all cases, conclusively ruled out their potential in ASW. Availableboth US and Soviet, concerning non-acoustic detection methods Indicates that noneapability for detecting submarines at long ranges comparable to that of SOSUS, although some could improve tlie potential of mobile units.
Over the next ten years, we expect improvements in Soviet ASW capabilities which may permit detection of US SSBNs during limited area searches of the open ocean or in confined areas the SSBNs must transit. We do not believe Soviet advances in either acoustic or non-acoustic techniques will provide them with an effective capability to detect US submarines at long ranges, although we do not rule out the possibility that they may be able toew.'
1 The Director of Nival Intelligence believe* thm tbc potential for the development ofrangewhen deployed on multiple platforms, may pro
utiiT solution to the Soviets' open ocean detection problem, and coniequentiy couldhreat to at leait some portion ol the USocce.
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SUMMARY
There are several conventional methods for detecting submerged submarines. Historically, acoustic systems have been predominant; these can be active or passive, fixed in tlie water or carried by ships and aircraft. Current non-owusfic tecluiiqucs include the use of radar, visual observations, intercept of electronic emissions, magneticdetection, and detection of the wakes made by the movement of submarines. ^
Present Capobilities
The Soviet Navy's submarine detection capabilities lag those of the USide margin. The principal weakness lies in the lackapability to detect submarines at long ranges within the broadof open ocean areas.
Geographic considerations in most instances inhibit Sovietof an acoustic system comparable to the US SOSUS arrays, which require sound channels found generally in water greater than 2in depth. Moreover, the effectiveness of SOSUS depends on the high-radiated noise levels made by the movement of Soviet nuclear submarines; US submarines are relatively quiet.
The Soviet effort in acoustic systems, winch arc fixed in the water. Is concentrated oh moored sensors. These are now primarily In coastal waters and are effective only at short ranges.
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The VICTOR and UNIFORM classes of atUck submarines now are the Soviets' most effective Soviet ASW platforms. They have the latest Soviet sonar systems. VICTOR Class submarines have tried to trail. US SSBNs leaving their bases. None of these activities has resultednown trail. The Soviets have employed their active sonar in this type of operation. This technique would facilitate overt trail once contact is established.
Most surface combatants in the Soviet Navy have some type of sonar. Combined ship and aircraft exercises, involving both helicopters and land-based patrol aircraft, are increasing. New construction and fitting of some older ships with modern sonars will generally improve the capabilities of the surface ASW force, although this force will not solve the open ocean detection problem.
Despite improvements in ASW capabilities, the Soviets stillolution to the fundamental problem of detecting US SSBNs in the open ocean. Reoojrnizing this, they continuefforts In both acoustic and non-acoustic methods of subinarine detection.ctivity appears to have high priority.
Acoustic systems which operateassharply limited because of the quietness of US nuclear submarines. This limitation will become even morn severe when noise levels are reduced even furtlier in new US SSBNs and when larger operating areas, permitted by future longer-range missiles in present and new SSBNs, are used.
Presentfforts should produce improvements in passive acoustic systems to include lower frequencies, some reduction ofself-noise, and advanced signal processing techniques, but these improvements are likely to be offset by US developments.
prove men Is arc expected in Soviet platform-mounted active sonars also; however, power requircrnents for long-range active sonar systems apparently preclude their use in long-range open ocean detection.
fforts on microwave radar are aimed atthe effects on the water's surface caused by the passageub-nvergedis method of detection is less susceptible to degradation from weather condition, although less so than most other non-acoustic
Jlf the Soviets succeed in developing an operational radar system for the detection of surface effects, it could significantly improve aircraft search rates.
There is evidence ofnvolving infrared detection by an aircraft of the heatubmarine's wake. The Soviets have thecompetence to deploy equipment for this purpose within the next ten years.
lasers earned by aircraftotential application in submarine detection. There is no evidence that the Soviets arcaser as an ASW sensor, but Soviet competence in laser technology isto initiate such researchX
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The Soviets are investigating the detection of the turbulence inproducedubmarine
3't is unlikely that any of these methods will enable detection of submarines at long ranges.
A detection program under way in the USSR
Relies on theelectromagnetic fields^generatedubmarine in thefrequenciesthat it
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probably is limited to short ranges]
Jsystem could be deployed
in the. Prospect!
There are many uncertainties regardingfforts in ASW, but there appears toonsiderable investment devoted to theof both acoustic and non-acoustic means of submarine detection.
Technical limitations make it unlikely that the Soviets willong-range capability in the open oceans through acoustic methods. However, these efforts should result in improved capabilities of their ASW forces. Development of towed linear arrays using narrow baud signal processing, for example, is well within Soviet capabilities. We can also expect to see continued improvements of sortobuoys. low-frequency, high-power sonars, moored acoustic sensors, and signal processing.
Some of the improved acoustic detection systems could be effective in choke points such as tho Greenland-Iceland-UK gap. This hasin terms of possible Soviet attempts to trail transiting US SSBNs. Data obtained by fixed systems in these restricted areas might be relayed to attack submarines in the area which might then attempt to trail transiting US SSBNs using passive sonar. However, because US SSBNs will probably continue to be quieter than Soviet nuclearovert trail would be unlikely. Active sonar might be required to establish contact in any trailing operations. If contact were gained, evasive maneuversS SSBN would probably preclude an overt trail for moreew hours.
Then non-acoustic detection offers some prospect of improving tlieir ASW capabilities, including trailing, but none of the known methods will solve the problem of detection in the open
he most promising non-acoustic method is detection ofeffects by radar in aircraft. Despite the improved search rates that could result, substantially more aircraft than are now available would still be needed for sustained coverage, evenimited area such as (he Norwegian Sea. Coverage of US SSBNs in the North Atlantic, the Mediterranean and the Pacific would be still more difficult because of the lack of bases and the size of the areas.
ummarizes present and projected Soviet ASW systems, and indicates the areas where each might be employed. Ifsucceed, the Soviets will be much more capable of detecting SSBNs in the choke points of the Mediterranean Sea and Uvegap leading into the Norwegian Sea, mainly bymany passive acoustic sensors. To achieve real-time detections, the Soviets mustata relay system suchatellite. In theSea. these fixed sensors could be supplemented by aircraft using improved sonolmoys and radar, as well as infrared detection. Information from fixed sensors could help Soviet submarines operating near the choke points make contact on transiting SSBNs. Surface units could assist in these efforts.
We do not expect that Soviet detection capabilities hi the Pacific, Atlantic, or Indian oceans will improve significantly during the next decade because they will stillystem capable of monitoring broad expanses. The advent of longer-range US submarine-launched ballistic missiles (SLBMs) and expansion of SSBN operating areas will further complicate Soviet detection problems.
iv dorctot ol nml intelligence bel*ve* but ike potential tot tbe development olwhea deplored on multiple platformi. mf provide
amrfutttiihe sonets' open covin detection problem. comeauenlly could eonhreat to atlonte portion ot the us ssbn tm.-
The Soviets are continuing to searcholution to their open-ocean detection problem, and some of the noo-acoustjc sensors we see in theirffort may have potential for development Into an operational short-range, mobile system. While, we can foresee an overall improvement in Soviet ASW capabilities, the available evidence does not suggest that the Soviets will achieve an effective open ocean submarine detection capability within the next tenis, thereow probability that they will be able to detect patrolling US SSBNs. although we do not rule out the possibility that they willa capability toew."
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