The United States on Monday designated Iran's elite military force, the Islamic Revolutionary Guard Corps, a terrorist organization, ramping up already far-reaching attempts to undermine the Iranian government.
President Donald Trump said in a statement that the "unprecedented" move "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."
"The IRGC is the Iranian government's primary means of directing and implementing its global terrorist campaign," Trump said.
It is the first time the United States has designated part of a foreign government a terrorist organization, rather than guerrilla groups or other more informal entities.
The move comes on top of Trump's decision to pull the United States out of an international deal with Iran that was meant to lift crippling economic sanctions in return for the government allowing its nuclear technology to be restricted and kept under close supervision.
The Trump administration argues that Iran's government, which is locked in a deeply hostile standoff with top US ally Israel, cannot be trusted and should face "maximum pressure."
Israeli's prime minister, Benjamin Netanyahu, warmly welcomed the move by his "dear friend" Trump.
- Retaliation threat -
The terrorist designation for the Revolutionary Guards is meant to strike at the heart of the Iranian government's power structure.
The elite force was formed after the 1979 Islamic revolution with a mission to defend the clerical regime, in contrast to more traditional military units that protect borders.
At home, it has amassed strong political and economic influence.
Abroad, the Guards' prized Quds Force, named for the Arabic word for Jerusalem, supports Iranian allies, including Syrian President Bashar al-Assad and Lebanon's Hezbollah.
Iran's parliament has vowed to retaliate by passing an urgent bill putting American troops on its own terrorism blacklist, which already features the jihadist Islamic State group, the semi-official news agency ISNA reported.
"Even though we believe one should not play along with America's extreme acts, the reality is that we must retaliate," the head of Iran's influential national security and foreign policy commission, Heshmatollah Falahatpisheh, told ISNA.
A statement signed by a majority of lawmakers in support of the bill said any action against Iran's national security and its armed forces was "crossing a red line" and the US administration would "regret" its decision.
- Criminalizing contact with Guards -
Addressing reporters following Trump's announcement, Secretary of State Mike Pompeo warned all banks and business of consequences to dealing with the Revolutionary Guards from now on.
"The leaders of Iran are racketeers, not revolutionaries," Pompeo said. "Businesses and banks around the world now have a clear duty to ensure that companies with which they conduct financial transactions are not conducted with the IRGC in any material way."
A senior Trump administration official said the new measure would criminalize contact with the Guards and "enable our prosecutors to bring charges to those that bring material support to the IRGC."
"The IRGC is interwoven into the Iranian economy.… The safest course is to stop doing business with the IRGC. If you do business with the IRGC you run the risk of bankrolling terrorism," said the official, speaking on condition of anonymity.
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."
The dramatic escalation of Washington's attempt to undermine Iran's leaders comes on the eve of Israeli elections where close Trump ally Netanyahu is seeking to extend his 13 years in office.
Trump, who describes himself as the most pro-Israeli US president ever, has recently recognized Israeli sovereignty over the occupied Golan Heights, as well as previously moving the US embassy from Tel Aviv to the contested city of Jerusalem.
"Thank you, my dear friend, US President Donald Trump, for having decided to declare Iran's Revolutionary Guards a terrorist organization," Netanyahu said in a statement issued minutes after the White House announcement.
"Thank you for responding to another important request of mine, which serves the interests of our countries and countries of the region."