U.S. President Donald Trump said on Monday he would name Iran's elite Islamic Revolutionary Guard Corps a terrorist organization, in an unprecedented step that drew Iranian condemnation and raised concerns about retaliatory attacks on U.S. forces.
U.S. officials said the terrorist label, which takes effect on April 15, would make it a criminal offense in the United States to provide "material support" to the Revolutionary Guards, with violators subject to up to 20 years in prison.
Secretary of State Mike Pompeo warned that global banks and businesses "have a clear duty" to not work with the organization.
"The Iranian regime remains the world's leading state sponsor of terror, spending almost a billion dollars every year to support terrorism", the White House said. The move would be the first such designation by any USA administration of an entire foreign government entity.
The US has in the past blacklisted dozens of entities and people for affiliations with the IRGC, but not the organization as a whole.
"It displays an ambition by proponents of confrontation with Iran to restrict Trump's deal-making instinct, and also to make it as hard as possible for the next USA president to engage with the Islamic Republic". While the accord does not specifically ban those tests, US officials have said they violate the spirit of the deal.
The move follows Trump's decision to pull the United States out of a multilateral deal with Iran that was meant to lift crippling economic sanctions in return curbs on Tehran's nuclear programme.
In response to the USA move, Iran's Supreme National Security Council declared the U.S. a "state sponsor of terrorism" and U.S. forces in the region "terrorist groups", state media reported.
The IRGC's involvement in Iran's banking and shipping industries could complicate matters with U.S. allies including the European Union.
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But according to the recent Politico/Morning Consult poll , Americans who approve of Obamacare outnumber those who disapprove. All Senate Democrats opposed the move, and they were joined by two Republicans - Susan Collins of ME and Mike Lee of Utah.
Iranian Foreign Minister Mohammad Javad Zarif said on Twitter that the move was aimed at securing the re-election of Israeli Prime Minister Benjamin Netanyahu.
Mr Pompeo said its response was to "counter the Iranian regime's terrorism" and "help the people of Iran get back their freedom".
The IRGC oversees the country's ballistic missile program and has conducted several tests since the landmark 2015 nuclear deal between Tehran and world powers.
The U.S. has branded other foreign organizations as terrorists in the past, but this latest decision marks the first time the U.S. has directly targeted a state-run military group.
In 2007, the US Treasury designated the IRGC Quds Force, its unit in charge of operations overseas, "for its support of terrorism", and has described it as Iran's "primary arm for executing its policy of supporting terrorist and insurgent groups".
Another official said the force has "been a principal driver of violence on a vast scale for many decades" in an attempt "to reshape the Middle East in Iran's favor".
Their involvement in Iran's banking and shipping industries could complicate matters with USA allies including the European Union. Saudi Arabia, the United Arab Emirates, the United States and other countries have accused the guard of supplying the Houthis with long-range missiles, a charge it denies.
Iran warned it will take reciprocal action against Washington for its move against the Islamic Revolutionary Guard Corps (IRGC), the country's most powerful security organisation.
At home, the Guards have amassed sweeping political and economic influence, with Brian Hook, the State Department´s representative on Iran, citing estimates that they control up to half of the Iranian economy. Tehran has warned that it has missiles with a range of up to 2,000 km (1,242 miles), putting Israel and USA military bases in the region within reach.