The long-awaited deal to supply Russian S-400 air defense systems to India will likely be signed this year, as the sides only have to agree on the price now, Russia's Military-Technical Cooperation Service (FSMTC) said.

"At the moment, all the technical issues are already discussed and agreed upon. It only remains to find common ground regarding the price and conduct the necessary procedures," FSMTC head Dmitry Shugaev told Interfax. "I think that this year will get to the point of signing the relevant contract papers."

The $5.5 billion agreement to supply S-400 was reached on the state level between Moscow and New Delhi back in 2016, but a specific contract has not been signed yet. Earlier, FSMTC deputy head Vladimir Drozhzhov assured that "there's no talk of refusing the supplies" by the Indian side.

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"I wouldn't say that the signing is being delayed. The routine negotiating process is under way… price parameters are being determined," he said. India wanted to lower the price and the issue was discussed when Indian Defense Minister Nirmala Sitharaman visited Moscow earlier in April, he added.

Russian S-400 have piqued quite a bit of interest in recent years. Sales to China started earlier this year. Turkey is awaiting the arrival of S-400 systems in 2020 in a $2.5-billion deal, despite criticism and threats from its US and NATO allies, while deals with Saudi Arabia and Qatar are currently in the works.

S-400 Triumf, or the SA-21 Growler, according to NATO classification, is Russia's most advanced air defense hardware, with capabilities unparalleled by any other system in the world. Consisting of a set of radars, missile launchers and command posts, it can bring down tactical and strategic aircraft as well as ballistic and cruise missiles, at ranges up to 400 kilometers (248 miles).

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