Meaning

Attack submarines are naval platforms designed primarily for anti-submarine warfare (ASW), anti-surface warfare (ASuW), intelligence gathering, and sea-denial operations. Unlike SSBNs, they are tactical and operational assets, not strategic nuclear deterrents.

Types of Attack Submarines

A. Diesel-Electric Attack Submarines (SSK)

• Use diesel engines on surface and battery power underwater
• Smaller, cheaper, and extremely silent at low speeds
• When fitted with Air Independent Propulsion (AIP), they can remain submerged for up to 2 weeks

Key Features

• High stealth in littoral and choke-point waters
• Ideal for coastal defence, ISR, and sea-lane denial
• AIP-enabled SSKs can be quieter than nuclear submarines

Indian Examples

• Kalvari class (Project-75)
• Sindhughosh class (Kilo)
• Shishumar class (Type-209)

B. Nuclear-Powered Attack Submarines (SSN)

• Powered by nuclear reactors
• Virtually unlimited range and endurance
• Faster and capable of sustained deep-sea operations

Key Features

• Ideal for blue-water navy operations
• Can escort carrier battle groups
• Superior for long-range surveillance and tracking enemy submarines

Indian Status

• No indigenous SSN currently in service
• INS Chakra II (Akula class) leased from Russia, decommissioned in 2021
• INS Chakra III (Akula class) expected
• Indigenous Project-75 Alpha SSNs planned

Strategic Importance of Attack Submarines

• Sea-denial and area dominance
• Protection of Sea Lines of Communication (SLOCs)
• Intelligence, Surveillance & Reconnaissance (ISR)
• Tactical superiority in Indo-Pacific littoral zones

Ballistic Missile Submarines (SSBN)

Meaning

Ballistic Missile Submarines (SSBNs) are strategic nuclear platforms capable of launching Submarine-Launched Ballistic Missiles (SLBMs) armed with nuclear warheads. They form the most survivable leg of a nuclear triad.

Key Characteristics

• Nuclear propulsion for long endurance
• Designed for stealth patrols, not combat engagement
• Carry long-range SLBMs for assured retaliation
• Operate as second-strike platforms

SSBNs in India

• INS Arihant (S2)
  
  • India’s first operational SSBN
  • Part of Advanced Technology Vessel (ATV) programme
  • Carries:
    • 12 × K-15 SLBMs (750 km range) OR
    • 4 × K-4 SLBMs (3,500 km range)
• INS Arighat (S3)
  
  • Improved successor of Arihant
  • Enhanced missile and sensor capabilities
• S4 & S5
  
  • Under development / planning
  • Expected to carry higher-range SLBMs

Strategic Significance

• Completes India’s Nuclear Triad
• Provides credible minimum deterrence
• Ensures assured second-strike capability
• Enhances strategic stability in Indo-Pacific
• Reduces vulnerability to first-strike scenarios