After the US announced its move of labelling Iran's Revolutionary Guards as a terror group, Iran on Saturday (local time) threatened to retaliate by blacklisting the US Army "alongside the dreaded Islamic State" if Washington went ahead with its decision.

Heshmatollah Falahatpisheh, head of Iranian Parliament's influential national security and foreign policy commission tweeted: "If the Revolutionary Guards are placed on America's list of terrorist groups, we will put that country's military on the terror blacklist next to Daesh (Islamic State)."

CNN had earlier reported that the US' decision is a part of the White House's increasingly aggressive strategy towards Iran. The move that was formally under the State Department's purview earlier marks the first time when Washington has designated any foreign country's military as a terror group.

Ties between Iran and the US soured after Washington slapped a multitude of sanctions on Tehran, citing the latter's support to state-sponsored terrorism and conflicts.

On November 5 last year, the Donald Trump administration had imposed the "toughest-ever" sanctions on Iran's banking, energy and shipping industries, with an aim to alter the "behaviour" of the country's regime.

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