The US on Monday designated Iran's Revolutionary Guard Corps a foreign terrorist organisation, an unprecedented declaration against a foreign government that may prompt retaliation and make it harder for American diplomats and military officers to work with allies in the region.
It is the first time that the US has designated an entity of another government as a terrorist organization, placing a group with vast economic resources that answers only to Iran's supreme leader in the same category as al-Qaida and the Islamic State.
"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.
Secretary of State Mike Pompeo said the designation is intended to increase pressure on Iran, isolating it further and diverting some of the financial resources it uses to fund terrorism and militant activity in the Middle East and beyond. But, in addition to the potential for Iranian retaliation, it complicates a delicate balance for US personnel in at least two key countries.
No waivers or exceptions to the sanctions were announced, meaning US troops and diplomats could be barred from contact with Iraqi or Lebanese authorities who interact with Guard officials or surrogates.
The Pentagon and US intelligence agencies had also raised concerns about the impact of the designation if the move did not allow contact with other foreign officials who may have met with or communicated with Guard personnel.
Those concerns have in part dissuaded previous administrations from taking the step, which has been considered for more than a decade.
Critics of the hardline policy also see it as a prelude to conflict.
"This move closes yet another potential door for peacefully resolving tensions with Iran," said Trita Parsi, the founder of the National Iranian American Council. "Once all doors are closed, and diplomacy is rendered impossible, war will essentially become inevitable."
"It makes crystal clear the risks of conducting business with, or providing support to, the IRGC," Trump said. "If you are doing business with the IRGC, you will be bankrolling terrorism."
"Thank you for answering another of my important requests that serves the interests of our countries and of countries in the region."
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