India and Russia could agree to a trade deal for the sub-continental country to buy Russia's S-400 missiles later this week when the Russian president Vladimir Putin visits India. However, the purchase of the surface-to-air missile systems – which has been on the cards for a while – could see India invite sanctioning from the United States.
India could have sanctions levied against it under the Countering America’s Adversaries Through Sanctions Act or the CAATSA. The act was brought into effect in August 2018 by the American president Donald Trump. Speaking about the potential missile purchase by India from Russia, without being specific, a spokesperson for the US State Department mentioned, "We urge all of our allies and partners to forgo transactions with Russia that would trigger sanctions under the CAATSA."
The Reuters also quoted the same person further as, "The administration has indicated that a focus area for the implementation of CAATSA Section 231 is new or qualitative upgrades in capability – including the S-400 air and missile defence system."
India's interest in purchasing the S-400 missiles is to ensure that it gets an edge over neighbouring rivals, China and Pakistan. Incidentally, China which had purchased the S-400 missiles from Russia had had military sanctions imposed on it by the United States.
The purchase deal of the S-400 missiles is set cost over $5 billion. Meanwhile, the Indian defence minister Nirmala Sitharaman spoke about the purchase deal of the missiles and said, "Negotiation on S-400 air defence systems has been on for a long while and it is at a stage where it can be finalised.
We have a big legacy of buying defence equipment from Russia." President Putin will visit India for the annual bilateral summit at the Indian capital, New Delhi from 4th-5th October 2018.