India, Aug. 4 -- India on Monday responded to US President Donald Trump's threat to increase tariffs on the country for purchasing Russian energy by describing such moves as "unjustified and unreasonable" and asserting it would take all necessary steps to protect its national interests and economic security.

The response from the external affairs ministry came hours after Trump's outburst on social media over India buying "massive amounts" of Russian oil and selling it on the open market for "big profits". Trump contended that he would be "substantially raising" tariffs on India since the matter is linked to the killing of people in Ukraine by Russia.

This is the second time that Trump has threatened to impose unspecified penalties on I...