The first elements of the S-400 system have arrived in India, according to a Russian official who spoke to Sputnik on the condition of anonymity, adding that delivery of the first division would be completed by the end of 2021.

Mr Putin is expected to visit India for the annual summit in the first week of December. Apart from the focus on regional matters, particularly the events in Afghanistan, New Delhi maintains it has strategic cooperation with the United States and Russia. On the other hand, Washington has stated that it has yet to determine whether to grant India a Countering America's Adversaries Through Sanctions Act (CAATSA) waiver for the S-400s. For its operations against Ukraine, the United States labels Russia as an opponent alongside North Korea and Iran.

Implementing a 2018 agreement for Russia to provide India with S-400 air defence missile systems might put India in danger of U.S. penalties.

So far, the United States has been adamantly opposed to granting India a CAATSA waiver, with some officials advising New Delhi to abandon the agreement. On the other side, many campaigned for a waiver for India. Some senators in the United States have recommended that India be excluded from CAATSA in return for breaking ties with Turkey. To confront a Chinese threat, India says that the pact is vital.

 China has already deployed two S-400 squadrons in Tibet at the Ngari Gar Gunsa and Nyingchi airbases in Ladakh and Arunachal Pradesh.

In October 2018, India and Russia agreed to purchase five S-400 regiments for $5.43 billion. Two Indian Air Force (IAF) teams have already been trained by Almaz-Antey in Russia, ahead of the expected deliveries.

Because of numerous large-ticket purchases, India and Russia's defence trade has reached $15 billion in the previous three years.

Defence missile systems could put India at risk of sanctions by the United States.

As of yet, the United States has not given any indication that it intends to grant India a waiver under CAATSA.

In contrast, others called for a waiver to India. Some U.S. senators applied to exclude India from CAATSA while favouring cutting ties with Turkey for the same deal. India defends the deal is to counter a threat from China.

In Tibet, China has already deployed two S-400 squadrons at Ngari Gar Gunsa and Nyingchi airbase across Ladakh and Arunachal Pradesh, respectively.