The US has made clear to India that it is "discouraging" it from proceeding with its acquisition of S-400 missile defence systems from Russia but Washington will have to weigh "important geostrategic considerations" while taking a decision on growing calls for a presidential CAATSA waiver to New Delhi, President Joe Biden's nominee for Coordinator for Sanctions Policy has told lawmakers.

In October 2018, India signed a USD 5 billion deal with Russia to buy five units of the S-400 air defence missile systems, despite a warning from the then Trump administration that going ahead with the contract may invite US sanctions.

The Biden administration has not yet clarified whether it will impose sanctions on India under the provisions of the Countering  America's Adversaries Through Sanctions Act (CAATSA) for procuring the S-400 missile systems. CAATSA is a tough US law that was brought in 2017 and authorises the US administration to impose sanctions on countries that purchase major defence hardware from Russia.

James O'Brien, President Biden's nominee for the US State Department's coordinator for sanctions policy was asked at his confirmation hearing on Wednesday if the US experience with Turkey provided any warning or lessons on how to proceed with India.

The US has already imposed sanctions on Turkey under the CAATSA for the purchase of a batch of S-400 missile defence systems from Russia.

Following the US sanctions on Turkey over the procurement of S-400 missile systems, there were apprehensions that Washington may impose similar punitive measures on India. Russia has been one of India's key major suppliers of arms and ammunition.