The announcement was made by the minister of the state of defence Sripad Naik in a written statement in Lok Sabha.
India had signed the missile deal in October 2018 during Russian President Putin's visit. The deal was worth $5 billion ensuring the advanced long-range surface-to-air missile would become a key weapon in India's arsenal.
Asked about India facing American sanctions under the Countering America’s Adversaries Through Sanctions Act (CAATSA) law, Naik said, "Government takes sovereign decisions based on threat perception, operational and technological aspects to keep the Armed Forces in a state of readiness to meet the entire spectrum of security challenges."
However, the Trump administration had warned that the deal would have serious implications for India even though no specific details were put forward by the US. India feared US sanctions under the Countering America's Adversaries Through Sanctions Act (CAATSA) instituted by the US Congress on arms purchases from Russia, but it did not transpire after Indian officials communicated India's defence requirements to Trump's officials.
In fact, former US defence secretary James Mattis had expressed confidence that US and India would "work out the matter" concerned with the deal even as several US officials frowned at the Russian deal.
"India has been spent many, many years in its nonaligned status, and it's drawn a lot of weapons from Russia," Mattis had told reporters at the Pentagon when asked about the deal, adding, "we'll work all this forward."
S-400 is known as Russia's most advanced long-range surface-to-air missile defence system.
China was the first foreign buyer to seal a government-to-government deal with Russia in 2014 to procure the lethal missile system. Moscow has already started delivery of an undisclosed number of the S-400 missile systems to Beijing.
Recently, the Erdogan-led government procured the first batch of the S-400 missiles from Russia with more due to arrive in 2023 despite heavy criticism by US officials.