Iranian people gather to mark the anniversary of the seizure of the US Embassy, in Tehran

Thousands of Iranians chanting "Death to America" rallied on Sunday to mark the anniversary of the seizure of the U.S. Embassy during the 1979 Islamic Revolution and the imminent reimposition of U.S. sanctions on Iran's oil sector.

Students attending the government-organised rally in the capital Tehran, broadcast live by state television, burned the Stars and Stripes, an effigy of Uncle Sam and pictures of President Donald Trump outside the former embassy compound.

Hardline students stormed the embassy on Nov. 4, 1979, soon after the fall of the U.S.-backed shah, and 52 Americans were held hostage there for 444 days. The two countries have been enemies ever since.

State media said millions turned out for rallies in towns and cities, swearing allegiance to the clerical establishment and Supreme Leader Ayatollah Ali Khamenei. The figure could not be independently confirmed by Reuters.

Rallies are staged on the embassy takeover anniversary every year. But rancour is especially strong this time following Trump's decision in May to withdraw from world powers' 2015 nuclear deal with Iran and reimpose sanctions on Tehran.

The deal brought about the lifting of most international financial and economic sanctions in return for Tehran curbing its disputed nuclear activity under U.N. surveillance.

Trump said the deal was weak and favoured Iran. The other signatories - Britain, France, Germany, Russia and China - remain committed to the accord.

U.S. Secretary of State Mike Pompeo said the penalties set to return on Monday "are the toughest sanctions ever put in place on the Islamic Republic of Iran."

Interviewed on "Fox News Sunday," Pompeo said, "There's a handful of places where countries already have made significant reductions in their crude oil exports and need a little more time to get to zero. And we're going to provide that to them." He did not elaborate.

Pompeo noted that oil sanctions would be coupled with financial sanctions involving "over 600 designations of individuals and companies in Iran."

The Iranian military said it would launch two days of air defence drills on Monday and assured Iranians that it could neutralise any threats, the state news agency IRNA reported.

"We can assure our people that the enemy will not be able to carry out its threats against our country," IRNA quoted Habibollah Sayyari, the coordinating officer, as saying.

"DONALD SALMAN"

Among the anniversary events was an exhibition of cartoons in Tehran called "Donald Salman" - a reference to the close ties between the U.S. president and King Salman, ruler of Iran's regional rival, Saudi Arabia.

"It's black humour, but the audience can also be brought to reflect on the contradictions in the behaviour of Trump and (the royal house of) Al Saud," artist Masoud Shojaei Tabatabai told state television in Tehran.

The restoration of U.S. sanctions on Monday targeting Iran's oil sales and banking sector is part of an effort by Trump to force Iran to halt its nuclear and ballistic missile programmes outright, as well as its support for proxy forces in conflicts across the Middle East.

In a speech on Saturday, Khamenei said Trump's policies faced opposition around the world. "America's goal has been to re-establish the domination it had, but it has failed. America has been defeated by the Islamic Republic over the past 40 years," he said.