The U.S. Treasury announced Monday that it had sanctioned nine Iranians who are among supreme leader Ayatollah Ali Khamenei's inner circle for "advancing Iran's radical agenda," a move that seeks to block funds to those who "oppressed the Iranian people, exported terrorism and advanced destabilizing policies around the world."

The sanctions were handed down Monday and coincided with the 40th anniversary of the seizure of the U.S. Embassy in Tehran by student militants and the beginning of the Iran hostage crisis which lasted 444 days.

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"Today the Treasury Department is targeting the unelected officials who surround Iran’s Supreme Leader, Ayatollah Khamenei, and implement his destabilizing policies," Treasury Secretary Steven Mnuchin said in a statement. "These individuals are linked to a wide range of malign behaviors by the regime, including bombings of the U.S. Marine Barracks in Beirut in 1983 and the Argentine Israelite Mutual Association in 1994, as well as torture, extrajudicial killings and repression of civilians."

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"This action further constricts the Supreme Leader’s ability to execute his agenda of terror and oppression," Mnuchin added.

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The sanctioned individuals are Ebrahim Raisi, head of Iran's judiciary; Mojtaba Khamenei, the supreme leader's second son; Mohammad Mohammadi Golpayegani, Khamenei's chief of staff; Vahid Haghanian, a former military commander who is considered the supreme leader's "right hand;" Khamenei's senior advisor Ali Akbar Velayati; advisor Gholam-Ali Hadad-Adel; Iran's Armed Forces General Staff (AFGS) Chief Mohammad Bagheri; Islamic Revolutionary Guard Corps (IRGC) Brig. Gen. Hossein Dehghan; IRGC Commander Gholam Ali Rashid; and the entire AFGS staff, according to the treasury.

"This action seeks to block funds from flowing to a shadow network of Ali Khamenei’s military and foreign affairs advisors," the Treasury Department said.

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The State Department's most recent Country Reports on Terrorism, released Friday, stated that Iran is still the "world's worst state sponsor of terrorism," spending nearly $1 billion per year to support terror groups including Hezbollah, Hamas and the Palestinian Islamic Jihad.

Iran also plots its own terrorist acts around the globe, the department said.

On Tuesday, Iran's Atomic Energy Organization announced it would begin injecting uranium into 1,044 centrifuges, another violation of the 2015 nuclear deal. Tehran said it now operates 60 advanced centrifuges — twice as many as allowed under the accord.

Fox News' Cody Derespina and The Associated Press contributed to this report.