Members of the Iranian revolutionary guard march during a parade to commemorate the anniversary of the Iran-Iraq war (1980-88), in Tehran September 22, 2011.
In its declaration, the SNSC also invoke the ongoing carnage in Yemen being carried out by the US -backed Saudi coalition, and charged that the USA government and its allies "have always been advocates of extremist groups and terrorists" in the Middle East.
The move had also been met with internal resistance in the Trump administration because of concerns about U.S. troops in the Middle East.
The United States has long mulled designating the Revolutionary Guards as terrorists but held off, fearing threats to U.S. troops and questioning whether the move would do much to pressure a force already under a raft of sanctions. President Trump has publicly castigated Pakistan and cut off all aid to the country.
"This unprecedented step, led by the Department of State, recognizes the reality that Iran is not only a state sponsor of terrorism, but that the IRGC actively participates in, finances and promotes terrorism as a tool of statecraft", President Donald Trump said in announcing the measure.
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Another focus is whether Mueller will disclose anything from his inquiries into Middle Eastern efforts to influence Trump. But Barr's phrasing in that letter is somewhat ambiguous.
Administration officials have said the step will further isolate Iran and make clear that the USA won't tolerate Iran's continued support for rebel groups and others that destabilize the Middle East. The decision will take effect April 15.
Secretary of State Mike Pompeo.
Pompeo said the move is part of an effort to put "maximum pressure" on Iran to end its support for terrorist plots and militant activity that destabilizes the Middle East.
Mr Pompeo told reporters yesterday the USA would continue to sanction and pressure Iran to "behave like a normal nation" and urged America's allies to take similar action. The group, enshrined in the constitution, answers only to Iran's supreme leader.
In a later tweet, he added: "We must help the people of Iran get back their freedom".
"We will continue to increase financial pressure and raise the costs on the Iranian regime for its support of terrorist activity until it abandons its malign and outlaw behaviour".
But some Pentagon officials, including Joint Chiefs of Staff Chairman Gen Joe Dunford, had expressed concerns about troop safety, the Wall Street Journal reported.
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Retweeting Brown's criticism of Smith-Schuster, Reid declared that he respects Brown's skills, but can't wait to "smash" him. JuJu posted the following quote from author Mark Twain on Sunday afternoon, "Never argue with a fool".
The Central Intelligence Agency had also reportedly opposed the move.
In a statement carried on Monday by Iran's state-run IRNA news agency, the council said it also declared all U.S. forces operating in the Middle East "terrorist groups".
Part of America's vast military presence around the globe, CENTCOM's area of command covers multiple war zones and hotspots including Afghanistan, Iraq, Syria, Yemen, and the Gulf.
The State Department said on Monday the IRGC has been engaged in terrorist activity since its inception, including the 1996 Khobar Towers bombing in Saudi Arabia that killed 19 Americans, and a foiled plan to attack the Saudi ambassador to the United States on US soil.
Iran will take reciprocal action against the United States if Washington designates the elite Revolutionary Guards (IRGC) as terrorists, a majority of Iranian parliamentarians said on Sunday, according to state news agency IRNA.
A force of an estimated 125,000 men, it works in parallel to conventional military and reports directly to supreme leader Ayatollah Ali Khamenei.
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.
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Senior US politicians said they cautioned Mr Cavusoglu that deepening ties with Moscow "will risk sanctions and Turkey's involvement in the F-35 programme".