New Delhi: Defence Minister Nirmala Sitharaman on Tuesday said that the deal to purchase S-400 Triumf air defence missile systems from Russia has "reached almost the final stage".

The S-400 missile deal is a contentious deal as the United States is opposed to it. The US has imposed military sanctions against Russia under stringent CAATSA (Countering America's Adversaries Through Sanctions Act). This also extends to countries that engage with Russia in defence matters. US' stand effectively means that any country that engages in defence or intelligence sharing with Russia could also be subject to sanctions.

"The negotiation with Russia on the S-400 have reached almost the final stage, we'll have to see it if it's signed before the Russian President's visit. But the negotiations are almost complete," Sitharaman told media today.

During the 2+2 dialogue earlier this month, India told US that it would go ahead with the deal and sought waiver from sanctions.

On one hand, India wants these missiles to strengthen defence capabilities, but at the same time does not want to sour relations with the US. India would hope that the Trump administration grants the exemption to India under CAATSA. The waiver that India may seek will not be an easy decision for the Trump administration to make because of certain sections in the CAATSA legislation.

Section 231 the CAATSA legislation requires that the president impose sanctions on any entity that "engages in a significant transaction with the defence or intelligence sectors of the Government of the Russian Federation". With the value of the deal being almost Rs 40,000 crore, it definitely falls under 'significant transaction' mentioned in CAATSA.

Good news for India is that some sections in the Trump administration want the waiver to be granted to India. Reports say that Secretary of Defence James Mattis is a strong proponent of granting waivers to India.