The US is set to reimpose oil and financial sanctions against Iran, ratcheting up the pressure on Tehran to curb its missile and nuclear programs and counter its growing military and political influence in the Middle East.
The move will restore US sanctions that were lifted under a 2015 nuclear deal negotiated by the administration of President Barack Obama, and add 300 new designations in Iran's oil, shipping, insurance and banking sectors.
President Donald Trump announced in May that his administration was withdrawing from what he called the "worst ever" agreement negotiated by the United States.
Other parties to the deal, including Britain, France, Germany, China and Russia, have said they will not leave.
Secretary of State Mike Pompeo and Treasury Secretary Steven Mnuchin are set to announce details of the sanctions on Monday.
China, India, South Korea, Japan and Turkey - all top importers of Iranian oil - are among eight countries expected to be given temporary exemptions from the sanctions to ensure crude oil prices are not destabilised.
Washington has said it will ensure a well supplied global oil market, with help from ally Saudi Arabia, as Iran oil is cut back.
The reimposition of the sanctions comes as the United States is focused on US congressional and gubernatorial elections on Tuesday.
Campaigning in Chattanooga, Tennessee, late on Sunday, Trump said his "maximum pressure" policy against Iran was working.
"Iran is a much different country than it was when I took office," said Trump, adding: "They wanted to take over the whole Middle East. Right now they just want to survive."
Earlier, thousands of Iranians chanted "Death to America" at a rally to mark the anniversary of the seizure of the US Embassy during the 1979 Islamic Revolution.
The International Monetary Fund said on Thursday that Iran should implement policies to safeguard its macroeconomic stability in the face of sanctions.
Senior Iranian officials have dismissed concerns about the impact to its economy.
"America will not be able to carry out any measure against our great and brave nation ... We have the knowledge and the capability to manage the country's economic affairs," Foreign Ministry spokesman Bahram Qasemi told state TV on Friday.
