The United States imposed on Monday sanctions on Iran’s supreme leader Ali Khamenei and numerous military chiefs, looking for a fresh blow to Iran's economy after Tehran's downing of an unmanned American drone.
With tensions running high between the two countries, President Donald Trump signed an executive order imposing the sanctions, which US Treasury Secretary Steven Mnuchin said would lock billions of dollars more in Iranian assets.
Trump told reporters that the sanctions were in part a response to last week's downing of a US drone by Iran, but would have happened anyway. He said Khamenei was ultimately responsible for what Trump called "the hostile conduct of the regime" in the Middle East.
"Sanctions imposed through the executive order ... will deny the Supreme Leader and the Supreme Leader's office, and those closely affiliated with him and the office, access to key financial resources and support," Trump said.
The sanctions are aimed at denying Iran's leadership access to financial resources, blocking them from using the United States financial system or having access to any assets in the United States.
"Anybody who conducts significant transactions with these sanctioned individuals may be exposed to sanctions themselves," the White House said.
Signing the punitive financial measure, Trump called it a "strong and proportionate response to Iran's increasingly provocative actions."
Repeating that "never can Iran have a nuclear weapon," Trump said it was now up to Tehran to negotiate.
"We do not ask for conflict," he said, adding that depending on Iran's response the sanctions could end tomorrow -- or it "can also be years from now."
Mnuchin said Iranian Foreign Minister Mohammad Javad Zarif would be targeted with US sanctions later this week.
Sanctions were also imposed on eight senior commanders of Navy, Aerospace, and Ground Forces of the Iranian Revolutionary Guards Corps (IRGC), the US Treasury Department said.
"These commanders sit atop a bureaucracy that supervises the IRGC's malicious regional activities, including its provocative ballistic missile program, harassment and sabotage of commercial vessels in international waters, and its destabilizing presence in Syria," the department said in a statement.
In a pair of tweets Monday, Trump said US aims regarding Iran boil down to "No Nuclear Weapons and No Further Sponsoring of Terror."
But while some in Washington see the White House's ultimate goal as regime change in Tehran, Trump says he wants to avoid war and that he's open to negotiations with Iran's leaders.