India has strategically deployed Russian-built S-400 long-range air defence systems to protect the vulnerable Siliguri Corridor—a narrow 20-22 km stretch known as the "Chicken's Neck" that serves as the sole land connection between mainland India and its north-eastern states.

This deployment comes amid intensifying regional tensions, particularly with China's growing military influence in Bangladesh. The sophisticated S-400 system, capable of tracking aerial threats up to 600 km away and engaging targets at ranges up to 400 km, represents a significant reinforcement of India's defensive capabilities in this strategically critical region, effectively creating a protective shield over one of the country's most vulnerable military arteries.

India has also deployed its Rafale fighter jets close to the Sikkim-Bhutan-Tibet tri-junction on the eastern front with China. This deployment is part of India's strategy to enhance its military posture in the region and serve as a deterrent against Chinese aggression.

India has further fortified the Siliguri Corridor by deploying, BrahMos supersonic missiles.

Initially, there were discussions about deploying Rafales in the Ladakh sector amid the border row with China. However, the primary focus has been on strengthening the eastern front and other strategic locations.

Strategic Significance of The Siliguri Corridor

The Siliguri Corridor represents one of India's most critical and vulnerable geographic features. This narrow strip of land, just 20-22 kilometres wide at its narrowest point, connects mainland India to its northeastern states, which are otherwise surrounded by foreign territories including Bangladesh, Myanmar, China, and Bhutan. The corridor's strategic importance cannot be overstated—it serves as the only land bridge to India's resource-rich but geographically isolated north-eastern region, home to seven states often referred to as the "Seven Sisters."

The corridor's nickname—"Chicken's Neck"—aptly describes its vulnerability. Any disruption to this narrow passage would effectively cut off the northeastern states from the rest of India, creating severe logistical, economic, and defence challenges. This geographic vulnerability has long been recognized as a potential strategic liability in India's defence planning, particularly given the complex geopolitical environment of the region and historical territorial disputes with neighbouring countries.

The deployment of advanced air defence systems to this region represents India's acknowledgment of this vulnerability and determination to protect this critical juncture. By positioning one of its prized S-400 squadrons in this location, India aims to create a protective umbrella over the corridor, significantly reducing the risk of any potential aerial threats that could compromise this vital connection.

S-400 Air Defence System: Capabilities And Deployment Strategy

The S-400 Triumf air defence system represents the cutting edge of Russia's military technology and provides India with formidable defensive capabilities. Each S-400 squadron deployed by India consists of 16 vehicles, comprising launchers, radar systems, control centres, and support vehicles. This integrated system is designed to provide comprehensive protection against a wide range of aerial threats.

The system's impressive technical specifications include the ability to track aerial threats at distances of up to 600 kilometres and engage targets at ranges of up to 400 kilometres. The S-400 utilizes four different missile types, giving it remarkable versatility in responding to various threats. It can effectively intercept and neutralize fighter jets, ballistic missiles, and drones, making it a vital component of India's defence arsenal.

India secured these advanced systems through a ₹35,000 crore (approximately $5 billion) deal with Russia in 2018 for the procurement of five S-400 squadrons. As of early 2025, three squadrons have already been delivered and deployed at strategic locations across India's borders. The fourth squadron is expected to arrive by the end of 2025, with the final squadron anticipated in 2026, according to Defence Ministry sources.

The strategic deployment of these squadrons reveals India's defence priorities. One squadron has been specifically positioned to protect the Siliguri Corridor. Another is stationed in the Pathankot region, providing coverage for Jammu & Kashmir and Punjab against potential threats from both China and Pakistan. The third has been deployed along India's western border, ensuring protection for key locations in Rajasthan and Gujarat.

Tactical Advantages of The S-400 In The Siliguri Corridor

The positioning of an S-400 squadron at the Siliguri Corridor provides multiple tactical advantages for India's defence architecture. The system's extensive range creates an air defence bubble that extends well beyond Indian territory, allowing for early detection and neutralization of potential threats before they approach sensitive areas. This early warning capability is particularly crucial for the narrow corridor, where reaction time would be limited in case of an aerial attack.

The S-400's versatility in engaging multiple target types simultaneously ensures comprehensive protection against various threat vectors—from high-altitude bombers to low-flying drones or cruise missiles. This multi-layered defence capability is especially valuable in the complex terrain surrounding the Siliguri Corridor, which includes mountainous regions that could otherwise be exploited for surprise attacks.

Rising Regional Tensions: The China-Bangladesh Factor

The deployment of the S-400 to the Siliguri Corridor must be understood within the context of shifting regional dynamics, particularly the growing military cooperation between China and Bangladesh. This development has raised significant strategic concerns in New Delhi, as it potentially threatens to encircle India with Chinese military influence.

In recent years, Bangladesh has gradually shifted from its historical alignment with India toward closer ties with China. Beijing has supplied Dhaka's military with advanced equipment including fighter jets, tanks, and submarines, substantially enhancing Bangladesh's military capabilities. This arms relationship represents a significant shift in the geopolitical landscape of South Asia, as Bangladesh—a country that gained independence with India's support—increasingly leans toward China's sphere of influence.

Of particular concern to Indian strategists is the recent development of joint military exercises between Chinese and Bangladeshi forces. The People's Liberation Army (PLA) troops have conducted drills with their Bangladeshi counterparts at the Bangabandhu Bangladesh-China Friendship Exhibition Center near Dhaka. This unprecedented military cooperation signals a deeper strategic alignment between the two countries that could potentially compromise India's security interests.

India's response has included high-level diplomatic engagements. National Security Advisor Ajit Doval made a quiet visit to Bangladesh in February 2024, following Prime Minister Sheikh Hasina's party winning a fourth consecutive term. India's Foreign Secretary Vinay Kwatra also visited Bangladesh to strengthen bilateral ties, indicating India's diplomatic efforts to counter Chinese influence in its immediate neighbourhood.

Broader Geopolitical Implications

The deployment of the S-400 system to the Siliguri Corridor should also be viewed within the broader context of India's strategic competition with China. The corridor's proximity to Chinese territory in Tibet makes it particularly sensitive from a military perspective. China's territorial claims and infrastructure development along the Line of Actual Control (LAC) have heightened tensions, especially following the 2020 border stand-off in Ladakh.

Additionally, the influx of Myanmar soldiers seeking refuge in India—over 700 troopers since November 2023, with approximately 300 entering in January 2024 alone—adds another layer of complexity to the regional security environment. These developments collectively underscore the multifaceted challenges India faces in securing its north-eastern frontiers.

Future Deployments And Strategic Outlook

With India set to receive its fourth S-400 squadron by the end of 2025 and the fifth by 2026, the country's air defence capabilities will continue to strengthen significantly. The complete deployment of all five squadrons will create an integrated air defence network covering India's most strategically important regions and vulnerable points.

The timing of these deployments is particularly significant given the evolving regional security landscape. The escalation of tensions with China since the 2020 Ladakh stand-off has prompted India to accelerate its enhancement of air defence capabilities. The S-400 systems represent a crucial component of this strategy, providing a credible deterrent against potential aerial threats.

As these advanced systems become fully operational, they will substantially alter the military equation in the region. The S-400's exceptional range and capability to neutralize multiple types of threats simultaneously provide India with a significant advantage in protecting its airspace and critical infrastructure. This enhanced defensive posture not only secures vulnerable points like the Siliguri Corridor but also contributes to strategic stability by raising the costs of any potential military action against Indian territory.

Conclusion

India's deployment of the S-400 air defence system to the Siliguri Corridor represents a strategic response to evolving security challenges in its neighbourhood. The system's advanced capabilities provide a significant boost to India's ability to protect this crucial geographic vulnerability that connects mainland India with its northeastern states. This deployment must be understood within the context of growing Chinese influence in Bangladesh and broader regional tensions.

The sophisticated technical specifications of the S-400—including its extensive tracking range of 600 kilometres and engagement capability of up to 400 kilometres—make it particularly well-suited for defending the narrow Siliguri Corridor. By creating an extensive defensive bubble around this critical juncture, India aims to neutralize potential aerial threats before they can compromise this vital connection.

As India continues to receive additional S-400 squadrons through 2026, its comprehensive air defence architecture will provide enhanced security across multiple fronts. This strategic deployment reflects India's determination to secure its territorial integrity and protect critical infrastructure amid shifting geopolitical dynamics in South Asia.

IDN