The US has decided to sell High-Altitude Anti-Submarine Warfare (HAASW) sonobuoys worth Rs 4.38 crore to India, PTI has reported. According to the report, the sonobuoys will bolster India’s ability to address present and future threats by enhancing its anti-submarine warfare (ASW) capabilities.


Sonobuoys are air-launched, expendable, electro-mechanical sensors designed to relay underwater sounds to remote processors. These form effective and affordable anti-submarine warfare and are capable of being used by airborne entities.


”India will have no difficulty absorbing this equipment into its armed forces,” the Defense Security Cooperation Agency (DSCA), an organisation under the US Department of Defense, said in a notification to the Senate Foreign Relations Committee this week. The DSCA's mandate is to advance the US' "defence and foreign policy interests by building the capacity of foreign partners in order to encourage and enable allies and partners to respond to shared challenges".


Under the US' Arms Export Control Act, the Congress has 30 calendar days to review the sale. India had requested to buy AN/SSQ-53O HAASW sonobuoys, AN/SSQ-62F HAASW sonobuoys, and AN/SSQ-36 sonobuoys, as per PTI. 


This proposed sale will advance the foreign policy and national security objectives of the United States by reinforcing the strategic partnership between the US and India, the notification notes. It will also improve “the security of a major defence partner which continues to be an important force for political stability, peace, and economic progress in the Indo-Pacific and South Asia regions”, it added. 


On August 23, US Secretary of State Antony Blinken approved the foreign military sale to India of anti-submarine warfare sonobuoys and related equipment. 


This comes after the Indian Navy launched the fourth and fifth ships of the Eight Anti-Submarine Warfare Shallow Water Craft project, built by M/s Cochin Shipyard. According to the Defence Ministry, both the ships were launched on Monday in Kochi in the presence of Vice Admiral V. Srinivas, Flag Officer Commanding-in-Chief of the Southern Naval Command.


These ASW ships are equipped with state-of-the-art, indigenously developed underwater sensors, designed to perform anti-submarine operations in coastal waters, as well as low-intensity maritime and mine-laying operations. They are capable of achieving a top speed of 25 knots, with an endurance of up to 1,800 nautical miles.


Anti-Submarine Warfare & Sonobuoys 


An Anti-Submarine Warfare (ASW) passive sonar is meant to detect, classify and track sources of radiating sound. Passive sonars only listen and do not transmit any signals and are used in a variety of applications, including tracking and classification of marine mammals, earthquake detection as well as nuclear test ban monitoring.


According to a report in ThePrint, sonobuoys are dropped into the water by a naval helicopter or fixed-wing aircraft generally in a pattern. They are dropped in a canister and automatically get to work upon impact. Sonobuoys deployed in a pattern can detect the exact location of a submarine, which can then be tracked by other systems.


While some sonobuoys operate in passive mode, others work in active mode. The ones in active mode emit sound waves and listen to echoes that bounce back from underwater objects, such as submarines, transmitting the gathered data back to aircraft for analysis.