New Delhi: India will go ahead with the proposed purchase of five regiments of Russian-made S-400 Triumf advanced air defence system despite US concerns that the $5.5 billion (Dh20.1 billion) military deal could limit defence cooperation between New Delhi and Washington.

Defence Minister Nirmala Sitharaman on Tuesday said the negotiations between India and Russia to finalise the Rs390 billion deal were already in the last stage and won’t be hampered by the US red-flagging the deal for which the two countries signed an agreement in principle in 2016.

She said India had made it clear in all its engagements with the US that its ties with Russia were independent of external influences and relationships with other countries.

“I would like to make it clear here that in all our engagements with the United States, we have very clearly explained how India and Russia’s defence cooperation is something which has been going on for a very long time. It is a time-tested relationship. And India has got quite a lot of defence assets from Russia — assets, spares, servicing. We have a continuous relationship with Russia has been recalled.”

The Defence Minister’s remarks come days after a top US Congressmen, Republican Mac Thornberry, Chairman of the House Armed Services, told a group of journalists here that there was a lot of concern in both the Trump administration and the Congress regarding the S-400 missile system being acquired by any of America’s partners, including India.

Thornberry, who was in India last week, said if New Delhi went ahead with the purchase, it would complicate “our ability to work out inter-operability” at a time when the US had issued sanctions against Russian oligarchs and companies. These include Rosoboronexport, the state-owned Russian weapons trading company.

The Congressman said the US was making sanctions against Russia “flexible” for its allies like India to allow them breathing room to continue dealing with Moscow — but only to maintain their legacy equipment and at the same time they must wean themselves off Russian equipment.

He said a provision in the National Defense Authorisation Act (NDAA), which is awaiting a Senate nod after it was passed by the House on May 24, would allow the Trump administration to suspend the sanctions under the Countering America’s Adversaries Through Sanctions Act, or CAATSA, passed in August 2017 for Russia’s purported interference in the 2016 presidential election process.

But Sitharaman said the US sanctions were not binding on India. “We have also mentioned (to the US) that CAATSA cannot be impacting on us, on this particular characteristic of India-Russia defence cooperation. This has been explained.”

Asked about deal on the air defence system — a possible game-changer for its ability to counter ballistic missiles and stealth aircraft like those China is developing, the Defence Minister said: “That has been for a very long time in negotiations. We have reached a final stage in the S-400 negotiations. That explains it.”

Though Sitharaman didn’t mention about her meeting with Thornberry but a senior Defence Ministry official told IANS that the US Congressman was “clearly told” that the “CAATSA was your law” and India won’t abide by it.

The official said Thornberry also shared with the Defence Ministry CAATSA amendments granting partial waiver to countries like India.

“But the language was not acceptable and he (Thornberry) has been asked to modify it.”

India’s deep military and strategic ties with Russia date back to the beginning of the Cold War even as New Delhi led a movement of “non-aligned” countries that declared their tilt with neither Washington nor Moscow. However, India always leant toward the then USSR.

India still buys over 60 per cent of its defence equipment from Russia. At present, the Indian armed forces are 70 per cent equipped with Soviet or Russian weapons.