WASHINGTON: At the request of US Defense Secretary Jim Mattis , US lawmakers are working to get a waiver for India from the punitive Countering America's Adversaries Through Sanctions Act or CAATSA, under which sanctions kick off on countries that purchase significant military equipment from Russia.Though the act targets Russia, it is having its unintended consequences on India, which is planning to buy five S-400 Triumf air defense systems for around $4.5 billion from Russia, that US officials say could be considered as a significant military purchase.Republican Senator Dan Sullivan, a member of the Senate Armed Services Committee, yesterday told a Washington audience that Mattis has written a letter in this regard to Senator John McCain, who chairs this powerful committee, to come up with a legislative waiver for India.On questions during the Annual Leadership Summit of the US India Strategic and Partnership Forum (USISPF) here, Sullivan and Democratic Senator Mark Warner, who is vice chairman of the Senate Select Committee on Intelligence, said there is a desire among lawmakers to find some way to manage India's past commitment to Russia and its defense relationships with that country.Sullivan said he spent a lot of time a day with his colleagues in the House and Senate explaining the importance of getting legislative language right on CAATSA and that realignment of any relationship does not happen overnight. "One of the biggest proponents of the importance of this relationship is Secretary Mattis. And said, I need this (In his letter to Senator McCain). This is important for our country. This is important for India. This is important for the strategic relationships," Sullivan said."I'm hopeful that we're gonna get there on something that will advance our country's interests and advance India's interest ... and build that trust," Sullivan said as he called for concrete actions in Indo-US defense relationship.Responding to a similar question at a separate panel, Senator Warner, who is a strong proponent of CAATSA, said the lawmakers are looking into it and does not want India to suffer its unintended consequences."There are some with the view that the bill does allow flexibility. House version gives a little more on the waiver side. We are trying to investigate on the Senate side, how we can allow this military partnership to grow but not undermine the principles around CAATSA," Warner said in response to a question."It would be easier, I say to my Indian colleagues and friends, if this was simply parts of old aircraft that had been purchased 20 years before rather than a $4 billion plus air defense system. I do understand as well this was negotiated long before," he said, adding that this long relationship can't be broken overnight.Warner hoped that Indian colleagues will work with us so that we can continue the expansion of the professional relationship.