The U.S. on Monday sanctioned nine individuals and Iran's Armed Forces General Staff in a move targeting Iranian Supreme Leader Ali Khamenei's "inner circle" on the 40th anniversary of the Iranian hostage crisis.

Khamenei himself was placed under U.S. sanctions in June as part of the Trump administration's "maximum pressure" policy on Iran, which has seen sweeping economic penalties imposed on the Iranian economy and the country's officials and institutions.

Washington has been seeking new negotiations with Tehran on its nuclear program and other activities it considers destabilizing after President Donald Trump in May 2018 unilaterally withdrew the U.S. from the nuclear pact world powers struck with Iran. 

Iran started to cut its commitments under the 2015 nuclear deal in a retaliatory move following the U.S.'s unilateral decision to withdraw from the agreement between Tehran and the five permanent members of the UN Security Council plus Germany and the EU.

The deal allows Iran to reduce its commitments in case of other parties' breaches. Tehran insists the EU to act more actively regarding the implementation of its part of obligations, saying it will return to the full compliance with the deal once the EU has nullified the U.S. sanctions.

The new designations include Mojtaba Khamenei, the Iranian leader's son, whom the Treasury Department said is being blacklisted "for representing the Supreme Leader in an official capacity despite never being elected or appointed to a government position."

Gholam-Ali Hadad-Adel, the junior Khamenei's father-in-law and an advisor to the supreme leader, was also designated for working on his behalf.

Also sanctioned are Ebrahim Raisi, the head of the Iranian judiciary, Mohammad Mohammadi Golpayegani, Khamenei's Chief of Staff, and Vahid Haghanian, a top aide to Khamenei. 

"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.

Mohammad Bagheri, who was appointed to head the Iranian Armed Forces General Staff, was also placed under U.S. sanctions "for being a person appointed to a position as a state official of Iran by the Supreme Leader of Iran." The U.S. further designated two individuals whom it said have been intimately involved in Iran-directed terrorist attacks in the past. 

Hossein Dehghan, a brigadier general with Iran's Islamic Revolutionary Guard Corps, was the head of the corps' forces in Syria and Lebanon during the 1983 Marine Barracks Bombing in Beirut that killed 241 U.S. service members. 

And the department further blacklisted Ali Akbar Velayati, an individual wanted in Argentina on charges ties to the 1994 bombing of the Argentine Israelite Mutual Association, and whom the Treasury said has helped Tehran extend credit lines to the Syrian regime. 

As a result of Monday's sanctions, any property belonging to the proscribed entities subject to U.S. jurisdiction has been blocked and U.S. persons are generally prohibited from conducting business with them.