The United States on Monday expressed reservations about a proposed arms deal between India and Russia for five S-400 surface-to-air missile systems, The Hindu reported. The commercial negotiations for the deal, estimated to be around Rs 39,000 crore, concluded earlier this month.

“There is a lot of concern in the US, in both the administration and the Congress, over the S-400 system,” US Arms Service Committee Chairperson Mac Thornberry told reporters in New Delhi. “There is concern that any country and not just India that acquires that system will complicate our ability to work towards interoperability together.”

Thornberry visited India with a Congressional delegation that is on its way to the Shangri-La dialogue in Singapore.

These concerns, the legislator added, were separate from the sanctions and legislation that the US has imposed on Russia. He said the Donald Trump administration was making sanctions against Russia flexible for its allies such as India to provide them breathing room to continue dealing with Moscow so that they could maintain the equipment bought from Russia.

“The current sanctions bill that was just signed in the law last fall doesn’t really have much flexibility,” IANS quoted Thornberry as saying. “But the bill that passed by the House on Thursday adds more flexibility for nations like India who have a legacy of Russian military equipment and of course need to purchase spare parts in order to maintain the readiness of that equipment.”