The United States has slapped sanctions on nine people connected to Iran's Supreme Leader Ayatollah Ali Khamenei, among them his chief of staff, one of his sons, and the head of Iran's judiciary.
The U.S. Treasury Department said in a statement on November 4 that Washington also sanctioned Iranian armed forces General Staff.
The Treasury's announcement on November 4 came as Tehran said it had further scaled back its commitments under the 2015 nuclear deal with world powers, saying it is now operating twice as many advanced centrifuges banned by the agreement.
"Today the Treasury Department is targeting the unelected officials who surround Iran’s Supreme Leader, Ayatollah Khamenei, and implement his destabilizing policies," U.S. Treasury Secretary Steven Mnuchin said in the 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," Mnuchin said.
Among those targeted by the U.S. sanctions are Khamenei's chief of staff Mohammad Mohammadi Golpayegani and Vahid Haghanian, who the department said "has been referred to as the Supreme Leader’s right hand."
Treasury also said that Ebrahim Raisi, who Khamenei appointed in March to lead Iran’s judiciary, and Mojtaba Khamenei, Khamenei's second son, were also placed under sanctions.
The measures freeze any U.S.-controlled property or interests held by those targeted, and prohibit anyone or any entities in the United States from dealing with those sanctioned.
The United States also announced a reward of up to $20 million for information about former FBI agent Robert Levinson, who disappeared in Iran in 2007.
The State Department says Levinson was taken hostage in Iran with the complicity of the Iranian regime. Tehran has never acknowledged arresting him. Combined with a $5 million reward already in place from the FBI, this makes a total of $25 million available to whomever is able to provide information about Levinson.
The announcement came on the 40th anniversary of the 1979 student takeover of the U.S. Embassy in Tehran and the subsequent 444-day hostage crisis -- which the White House called a "brazen act."
It also came after Tehran said it now has a prototype centrifuge that works 50 times faster than those allowed under the deal, the head of Iran's Atomic Energy Organization Ali Akbar Salehi also said on November 4, adding that the moves would show Iran's "capacity and determination."
U.S. President Donald Trump last year withdrew the United States from the 2015 nuclear accord between Tehran and a group of world powers and has since reimposed and expanded punishing sanctions as part of a stated campaign of "maximum pressure" against Iran.
Meanwhile, Tehran has gradually reduced some of its commitments under the pact, which had curbed its nuclear program in exchange for sanctions relief.
It had warned previously that it would announce new steps in November.
Iranian officials complain that the remaining parties to the deal have failed to mitigate the effects of the U.S. sanctions.
Earlier on November 4, Iranian state media reported government-sponsored rallies in nearly 1,000 cities and towns across the country for annual commemorations marking the takeover of the U.S. Embassy in Tehran.
On November 4, 1979, Iranian militant students stormed the diplomatic mission and took 52 Americans hostage for 444 days after Washington refused to hand over Iran's toppled shah, Mohammad Reza Pahlavi, for trial in Iran.
The two countries have had no diplomatic relations since then.
"Today, we honor the victims of this brazen act," a White House spokeswoman said in a statement, adding: "The Iranian regime continues to target innocent civilians for use as pawns in its failed foreign relations."
"Until Iran changes this and its other hostile behavior, we will continue to impose crippling sanctions," the spokeswoman, Stephanie Grisham, said.
In Tehran, state television showed crowds packing the streets around the former embassy dubbed the "den of spies" after the 1979 Islamic Revolution. News agencies posted images of protesters setting the U.S. flag on fire.
Participants were chanting slogans against the United States, including “Death to America”, and Israel, according to the hard-line Fars news agency.
"Our fight with America is over our independence, over not submitting to bullying, over values, beliefs, and our religion," army chief Major General Abdolrahim Musavi said in a speech at the rally.
The United States "will continue its hostilities...unless it is crushed," Musavi said in remarks carried by state-run television.
Khamenei on November 3 renewed a ban on talks with the United States, describing the two countries as implacable foes.
"Those who believe that negotiations with the enemy will solve our problems are 100 percent wrong," Khamenei was quoted as saying by domestic media.
Trump wants to force Iran to renegotiate the 2015 nuclear accord, arguing that the terms were not tough enough to prevent the country from developing nuclear weapons, agree curbs to its ballistic-missile program, and end its "malign" activities in the Middle East.
Iran has denied it supports insurgent activity and said its nuclear program was strictly for civilian energy purposes. Iranian officials have also ruled out any negotiations on its missile program.