In October 2018, India had 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 might invite US sanctions.

The United States is encouraged by Indian efforts to diversify the purchase of its military or defence articles, the Pentagon has said.

It, however, also expressed concerns over the decision of New Delhi to purchase the S-400 missile defence system from Russia.

“We have been very clear with our Indian partners about our concerns over this purchase and encouraging them, as we urge many others not to purchase Russian equipment,” Pentagon Press Secretary John Kirby told reporters at a news conference on Monday.

“We remain encouraged by India's continued diversification of their defence equipment over just the past decade. So, we will continue to have that conversation with India's needs,” he said in response to a question. “We have made it very clear to India about our concern on this particular purchase,” he said when asked about India's decision in this regard.

In October 2018, India had 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 might invite US sanctions.