Even though it is not clear whether India will receive a waiver with regard to US sanctions against Russia, New Delhi has made it clear that it will go ahead with the S-400 air defence system deal as it is at an "advanced stage."

New Delhi — A defence analyst has suggested that America's reservations against India acquiring the Russian air defence system is mainly borne out of the fear that if the S-400 is used to test the stealth capabilities of American fighter jets, India would have access to the data of American jets and that data could be leaked to Russia or other adversaries of the US.

Former squadron leader of the Indian Air Force and an independent defence analyst Vijainder K Thakur confirmed that S-400 systems can be used not only to identify radar tracks belonging to America's F-35s, but to also possibly determine the configuration of an F-35.

"US aircraft like the F-35 Lightning 2 does not feature all aspects of stealth. The aircraft is optimized for front aspect stealth to make it invisible to adversary fighter X-band radars approaching head-on. From the side and rear aspects, the aircraft is not perfectly stealthy. Ground-based radars, such as the S-band 91NE6 acquisition and battle management radar of the S-400 system, can detect and track the F-35 because they would be rarely located head on to the F-35. The 91NE6 radar could record the various radar signatures of the F-35 and store them in an electronic library. The stored signatures could be used by other S-400 systems or other ground-based radars not only to identify a radar track as belonging to an F-35 but to also possibly determine the configuration of the F-35. For example, whether it is with or without external stores," defence analyst Vijainder Thakur told Sputnik.

However, sources in India's Defence Ministry said that the US has nothing to worry about.

"This fear is false and unfounded. India does not have a track record of supplying or passing defence technology of one country to the other. Nobody including the US can ever accuse India of this. The US has been selling defence equipment to India over the last one-and-a-half decades. But none of this defence technology has reached any other foreign country. In fact, a mix of defence equipment from Russia, USA, France, and Israel have worked well for the Indian military," an official in India's Defence Ministry told Sputnik on condition of anonymity.

A radar signature electronic library is a very closely guarded secret. There is no question of the Indian Air Force sharing its radar signature library with the Russian Air Force. If the US is skeptical about India's ability to guard its secrets, it would choose not to share its F-35 assets with the Indian Air Force or Indian Navy, he added. 

Another source told Sputnik that this, on the other hand, establishes the fact that the S-400 system is sophisticated defence equipment with hardly any parallel at this stage. The S-400 system has proved its worthiness in theatres of war and this has influenced India and other countries like Turkey, which has an entire line of US F-series fighter jets, to enter into negotiations with Russia to purchase the S-400 system. The US is particularly upset with Turkey as Turkey is a NATO member and mainly has US arms.

The US military-industrial complex is worried as more and more countries are showing interest in purchasing the S-400 system. Firstly, this would imply that US anti-missile defence systems are losing market share to S-400 if more and more countries acquire the S-400 as no US system to date can match its calibre. Secondly, the US defence establishment is worried that countries that buy the S-400 system and also have US fighter jets or are planning to acquire US fighter jets will pose a challenge for Washington, the source added.

Negotiations between India and Russia on this multi-billion dollar deal have reached an advanced stage and it is understood that a contract could be signed during the forthcoming Indo-Russian annual summit during the first week of October. China has already sealed a deal with Russia to purchase the S-400 system.