US President Donald Trump has designated Iran’s elite Revolutionary Guard Corps (IRGC) as a foreign terrorist organisation.
It is the first time the US has labelled another nation’s military as a terrorist organisation.
Iran retaliated by declaring US forces in the Middle East as a terrorist organisation, Iran state news reported.
Washington-Tehran tensions have risen since Mr Trump withdrew the US from the international Iran nuclear pact.
Labelling the Guards as a terrorist organisation will allow the US to impose further sanctions – particularly affecting the business sector, given the IRGC’s involvement in Iran’s economy.
A number of IRGC and affiliated entities have already been targeted by US sanctions for alleged proliferation activities, support for terrorism and human rights abuses.
What did President Trump say?
Mr Trump’s statement on Monday said: “This unprecedented step, led by the Department of State, recognises 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.”
The president added that the move was meant to “significantly expand the scope and scale” of pressure on Iran.
“If you are doing business with the IRGC, you will be bankrolling terrorism,” Mr Trump said.
The measure will take effect in one week’s time, according to the State Department.
Was there any dissent in the Trump administration?
US Secretary of State Mike Pompeo and National Security Adviser John Bolton, both Iran hawks, championed the decision, but not all US officials were so supportive.
Mr Pompeo told reporters on Monday the US will continue to sanction and pressure Iran to “behave like a normal nation” and urged America’s allies to take similar action.
“The leaders of Iran are not revolutionaries and people deserve better,” Mr Pompeo said. “They are opportunists.”
In a later tweet, he added: “We must help the people of Iran get back their freedom.”