The Iranian parliament yesterday approved the inclusion of the United States Central Command, known as CENTCOM, on its list of terrorist groups.
This came in response to US President Donald Trump's decision to include the Iranian Revolutionary Guards on the list of foreign terrorist groups.
Parliament also approved a bill authorising the government to take firm and repressive measures to counter the US forces' "terrorist acts that endanger Iran's interests", state television reported.
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"The government must take legal, political and diplomatic action in response to American actions," it said.
The semi-official Tasnim news agency reported that as many as 168 of the 210 Iranian Parliament members voted in favour of the bill.
Tensions between Tehran and Washington have been on the rise since last year when Trump unilaterally withdrew from the 2015 nuclear deal signed between Iran and the six major powers. The US has also re-imposed sanctions previously lifted under the agreement on Tehran.