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bas-tion n. 1: a fortified area or position that is considered to be a stronghold

Strategic nuclear weapons systems are under intense review. This review is motivated by the changing world political climate, domestic economic and budgetary demands, and increasingly difficult technical challenges in maintaining a credible landbased strategic deterrent in an era of highly accurate missiles. SSBN submarines comprise a potent and central element of both the U.S. and the Soviet Union’s strategic ballistic missile arsenal. The likelihood of a preemptive, short-notice nuclear war appears genuinely to have decreased. The prospects or protracted, low-level conventional military conOlcts that raise the risks or Inadvertent nuclear escalation caD.DOt be discounted. While not attempting to predict the outcome of the current strategic weapons systems debate, it is likely that SSBN’s will continue to play a central role in future strategic political and military policy debates. Consequently, an examination of Soviet SSBN operational strategies is appropriate.

Increasingly quiet and capable, the Soviet Union’s SSBN force structure and deployment strategy pose a unique challenge to U.S. warfighting capabilities. The 1989 Soviet Militarv Power summary published by the Department of Defense continues to indicate that a significant number of Soviet submarines are deployed in coastal bastions – namely, the Barents Sea and the Sea of Okhotsk. The 1988 summary outlines this strategy, and provides estimates of the actual SSBN force levels deployed in each area; those estimates are provided in Table 1. A deployment strategy that holds SSBN’s in areas that are in close proximity to land-based defensive forces of the Soviet Union may significantly reduce the risk to them of the U.S. surface and airborne ASW pressures. The inherent stealth and mobility of the attack submarine makes it the ASW platform of choice, and necessity. This article explores these bastions, and attempts to provide some perspective on some of the challenges U.S. submarines might face if called upon to contest this strategy.

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Bastions have rarely fared well in land combat. Immobile and frequently by-passed or neutralized, land bastions often provided security to the occupants only in times of peace. Soviet strategic submarine bastions incorporate attributes similar to those historically sought on land; namely,

  • Controlled access.
  • Defensive cover in depth.
  • Bolt holes (escape routes) for the SSBN’s in case the first two defense strategies fail.

The inherent stealth and mobility of nuclear submarines, however, inject new dimensions to the bastion concept. Consider now, the attributes of Soviet submarine bastions from a U.S. submarine’s ASW perspective.

Submarine Access Into Soviet Bastions
The Barents Sea and the Sea of Okhotsk are contiguous to the Soviet land mass and sheltered from the open ocean by island formations along the seas’ ocean-facing perimeters. The Soviet Union’s three major deep-water, ocean-access ports (Murmansk, Vladivostok, and Petropavlovsk-Kamchatskiy) all are located in or near these marginal seas, making the Barents and the Sea of Okhotsk prominent in any naval warfare planning. The general geography of both seas establishes natural ASW barriers that can be exploited by the Soviet Union to channel access into the postulated SSBN deployment areas through a few, defensible routes.

The principal passages into the Barents Sea (from the Norwegian Sea to the west, and the Arctic Ocean from the north) are relatively shallow (less than 1300 feet deep), and easily accessible from either the Soviet mainland or nearby islands within easy reach from the Soviet Union.

Access into the Sea of Okhotsk is more restricted than into the Barents Sea. Entry from the west is hindered by Sakhalin and Hokkaido Islands, and from the south and east by the Kuril Islands and the Kamchatka peninsula. The principal western approaches are through the Tatary Strait between Sakhalin Island and the Soviet mainland, and through La Perouse Strait between Sakhalin and Holckaido, Japan. Navigable passages are available between some of the Kurils. The Kuril Island passages are more narrow than those of the Barents, but are significantly deeper, with some passage depths approaching 900 fathoms.

Both the Barents and the Sea of Okhotsk have extensive shallow water areas where average depths are less than 100 fathoms (Figures 1 and 2). Ice cover is an important tactical consideration in both areas during winter when much of the surface area of both seas is ice-covered. The winter ice cover in the Sea of Okhotsk is widespread, frequently extending out into the Pacific off the Kurils and the Kamchatka peninsula. The Kola peninsula coast of the Barents Sea (off Murmansk) remains relatively ice-free during the winter, with the remainder of the sea ice covered. All of the Sea of Okhotsk and all but the northernmost area above Spitsbergen and Franz Joseph Land in the Barents are ice-free during the summer.

The Barents Sea’s varied bathymetry reflects the effects of extensive glaciation during the last glacial period. Significant bottom relief features resulting from that glaciation include submerged troughs and ridges, and coast lines that are broken by numerous fjords. The potential operational implications are discussed in a later section.

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Jane’s Underwater Warfare S,ystems 1989·90. credits the Soviet Union with significant ASW mine capabilities. Invento· ries are estimated to include a deep·water 1000-fathom deploy· able vertically·rising acoustic influence mine as well as shallow water magnetic, electric influence, and contact mines. Soviet MilitaD’ Power postulates that ASW mines may be an integral part of the defensive strategy for their coastal bastions. The combination of naturally-restricted access into the Barents Sea and the Sea of Okhotsk, the close proximity of these areas to the Soviet mainland, and the ready availability of ASW mine resources makes an aggressive defensive ASW mining strategy a credible military option. Such a strategy would significantly challenge safe, unrestricted U.S. submarine access into these areas were mine barriers actually deployed and activated.

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Defensive Cover Ia Depth
The Barents Sea and the Sea of Okhotsk are home to major organizational components of the Soviet Union’s naval surface, air, and submarine ASW assets. The Defense Department’s annual review of Soviet military power identifies several major military ground combatant, naval, and air facilities near Munnansk in the Barents, and Petropavlosk-Kamchatskiy, Sovetskaya Gavan, and Vladivostok in the Sea of Okhotsk areas. Geographic atlases show that both seas are also ringed by commercial and secondary airfields capable of handling up to commercial-sized aircraft. Helicopters could readily be deployed from any of these aviation facilities. Some of these secondary fields might also be capable of handling intermediate-range ASW aircraft such as the MAY as well.

The combination of favorably positioned in-place organic surface and submarine ASW forces together with an ASW aircraft surge deployment option provides a defense-in-depth for both submarine bastion areas. Defensive minefields could provide both an initial early warning and possible attrition of non-Soviet submarines entering either sea. Defensive minefields could have the additional impact of shepherding entering submarines into pre-defined ASW prosecution areas. Submarine contact datums in these ASW free fire zones could rapidly be prosecuted. Such a coordinated, multiple ASW platform defensive strategy, if successful, could reasonably be expected to help insulate bastion-deployed Soviet submarines from U.S. or Allied ASW pressures during a future conflict. Bolt Holes for Soviet SSBNs

Medieval fortresses are renowned for secret passageways bolt holes for the owners to use to escape or hide should the fortress defenses fail. The Barents Sea and the Sea of Okhotsk offer a strong natural analogue to this concept. As presented earlier, the bathymetry of the Barents Sea reflects the effects of heavy glacial activity during the last ice age. Numerous deep-water fjords are found along the Kola, Novaya Zemlya, and Franz Joseph Land coasts. The deep water axes of many of these fjords extend out into Barents Sea, the results of glacial scouring. As the ancient ice sheets moved offshore, sediments from the coastal shelves were deposited at many locations in the Barents basin. The periodic advance then retreat of ice left an almost corrugated landscape of depositional ridges and meltwater erosional valleys. Many of these nowsubmerged features have a relative relief of 50 fathoms or more. Examples include the Novaya Zemlya Trough east of Novaya Zemlya, the Kanin Trough northeast of Murmansk, and the Dyprent depression extending seaward from the Parsanger fjord at North Cape, Norway. The submerged channels are often flanked by shallow banks, potentially affording an evading submarine opportunities to exploit topographic shielding from search sensors.

The Sea of Okhotsk reflects a different geologic history. The sea itself was closed off from the Pacific by volcanic islands (the Kuril Islands) landward of the Kuril-Kamchatka ocean trench. There the bottom of the Sea of Okhotsk rises from 1500 fathom depths along the Kuril Islands in the south to broad, shallow shelves to the north. Several large gulfs and bays indent the coastline, sometimes leading to protected, deeper water small basins such as the Shelikhova Gulf in the northeast. Several shallow water banks north of Sakhalin Island also create isolated pockets of navigable deepwater off Iony Island southwest of Okhotsk and Magadan. AU of these areas offer naturally-sheltered havens for deployed submarines. Should the Soviet Union elect to deploy defensive minefields in the Sea of Okhotsk, these naturally-occurring evasion opportunities could be significantly enhanced.

A Question or Mines
The defensive ASW mining option figures prominently in both the Barents Sea and the Sea of Okhotsk. The geographic configuration of the Barents Sea and the Sea of Okhotsk encourage the use of mines as front-line defensive systems. The benefits could be many. Mine fields placed within the primary entry passages could provide some initial attrition of ingressing hostile (U.S. or Allied) submarines, and could also help improve ASW cueing by concentrating inbound submarines through the few deep entry passages. Mine fields within the seas themselves could also be used as they were during the Second World War as defensive barriers to protect SSBN deployment areas or escape routes. According to R C. Duncan, in America’s Use of Sea Mines, the U.S. and Great Britain laid over 300,000 offensive and defensive mines during World War ll. By early 1942, the U.S. Army had completed the laying of defensive mine fields off the major ports in the northeast U.S., San Francisco, . and the Panama Canal. These mine fields were remotely controlled from shore to allow transit to known, friendly vessels Similar remotely controlled mine fields in either the Barents or the Sea of Okhotsk would pose a serious mobility problem to U.S. submarines attempting to operate in Soviet submarine bastions. Soviet submarines, on the other hand, could be allowed to operate at will over the entire areas.

Mines can serve as either defensive or offensive weapons. Consider the U.S. Command’s offensive mine campaign in the Pacific Theater against Japan’s sea lines of communication with southeast Asia. It is interesting to note that the tonnage lost to offensive mines with minimal U.S. platform losses is almost half the total lost to direct submarine combat in the Pacific.

The effectiveness of submarine-deployed, offensive mine fields during World War II with relatively unsophisticated mines raises the prospect that offensive submarine mine operations might offer a possible counter to bastion-sequestered targets. Unfortunately, mines are indiscriminate weapons whose effectiveness is strongly dependent upon the number of mines used, whether the mines’ presence is known, and the number density of targets. Target selection and priorities cannot be ensured, and large numbers of mines might be required if used over broad areas of the Barents or Sea of Okhotsk. Therefore, the value of offensive submarine mining relative to the use of that weapon space for torpedoes is an open question.

The Submarine’s Perspective of Soviet Bastions
History has not been kind to faxed, military defensive systems. The Maginot Line was rendered ineffective by highly mobile German armor. The guns of Singapore were outflanked by a landward attack by the Japanese. Japan’s Pacific island fortresses were by-passed by a U.S. “island-hopping” strategy. Numbers, technology, and tactics all work to the benefit of the offensive combatant.

Yet, a Soviet SSBN bastion deployment strategy will present formidable challenges to a viable, forward-oriented maritime policy in a major conflict The combination of large, naturallyprotected geographies, the ready availability of combined-arms ASW defensive cover, and the inherent mobility of the real target – the Soviet SSBNs – all will work against a U.S. strategic ASW campaign. The implications of permitting Soviet strategic submarine bastions to go unchallenged are, however, severe:

  • U.S. surface and air ASW forces would effectively be eliminated as viable options in the heavily defended bastion areas, leaving U.S. SSNs to bear the brunt of a bastion ASW campaign.
  • U.S. SSNs would be left to press the anti-SSBN campaign while operating in a severe, combined-arms defensive ASW cover, a cover that in all probability could see an extensive use of ASW mines.
  • By using air and surface defensive ASW forces in the bastion area to help protect their SSBNs, the Soviet Union creates the option to release front-line SSNs otherwise employed in pro-SSBN operations for out-of-area offensive missions compounding the demand for U.S. SSNs already pressed to the forward areas.

Whatever the outcome of contemporary events in the Soviet Union and its allies, we must not lose sight that the U.S. attack submarine force must remain capable of exerting military pressure on Soviet SSBNs, whatever their deployment strategy may be. A critical examination of technological, tactical, and offensive options must be made to develop a viable submarinebastion counter. The strategic military and political implications of acquiescing the bastion areas are simply unacceptable .

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