The U.S. on Monday will restore major sanctions against Iran that had been suspended under former President Barack Obama's 2015 nuclear deal, threatening to further unravel the Islamic country's already-struggling economy.

Thousands protested across Iran throughout the weekend, as soaring unemployment and poverty prompted demonstrators to torch police vehicles and burn tires. At least one person was shot and killed in the protests, with some shouting "Mullahs get lost!" and "Death to the dictator!" the Fars news agency reported.

Even more severe U.S. sanctions against Iran's banking and energy sectors are slated to go into effect in November, including restrictions on Iran's oil industry that could cut off a crucial source of hard currency. The sanctions that will be re-imposed Monday target Iranian trade in automobiles, gold and other key metals.

President Trump formally withdrew from the Iran nuclear deal in May, after lambasting it repeatedly as a "horrible" arrangement that enriched the anti-American Islamic state without adequately ensuring it would never produce nuclear weapons.

The White House has said its goal is a new accord that would include a radical transformation of Iran's policies, including its military support for the Syrian government and regional militant groups, two issues not covered by the 2015 deal.

Trump has identified apparent leverage: Iran's economy, which has rapidly deteriorated in recent months due in large part to uncertainty over the Iran deal. The Iranian rial has fallen to 99,000 to the U.S. dollar despite a government-imposed rate of 44,000.

The president highighted the country's struggles on Twitter this week, even as he reiterated that he would be willing to meet with Iranian President Hassan Rouhani.

"Iran, and it's economy, is going very bad, and fast!" Trump wrote. "I will meet, or not meet, it doesn't matter - it is up to them!"

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Speaking on Fox News' "Sunday Morning Futures," former Connecticut Sen. Joe Lieberman, who has long criticized Obama's Iran deal, said Monday will be a "very important day -- and a day I didn't think would happen."

"Tomorrow is the day that, effectively, the Iran nuclear agreement of 2015 dies," he said. "This is one death I am not mourning because I thought it was a bad agreement. I thought we gave away a lot."

Lieberman added that Trump's bargaining position is sound, and that there could be a "second Iranian revolution" if hardliners there don't start negotiating with Trump to resolve the economic crisis.

"I give credit to President Trump on this one, for getting us out of the agreement," Lieberman said. "Hopefully it will bring the Iranians back to the negotiating table. ... The regime in Tehran has a lot of troubles. The economy is tanking."

Iran is negotiating with other world powers that are parties to the deal — China, Russia, Germany, France, Britain as well as the European Union — in a bid to salvage it with new incentives.

Meanwhile, tensions remain high. The country's powerful Revolutionary Guard on Sunday acknowledged conducting recent naval exercises near the crucial Strait of Hormuz after renewing threats to cut off the waterway to oil traders.

The nuclear deal lifted international sanctions in return for Iran limiting its nuclear program and allowing regular inspections. U.N. inspectors said Iran was complying with the deal.

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Iran "has treated its people very poorly, and that's led to terror. They're the world's largest state sponsor of terror. That's what America is trying to get Iran to stop doing. That's the behavioral change that we're looking for from the Iranian regime," Secretary of State Mike Pompeo told Metro TV in Jakarta.

"The president has always said he is prepared to talk, but it's important that Iran has to be committed to changing its ways in order for those discussions to prove of any value," he added.

Iran acquired five new ATR72-600 commercial aircraft on Sunday, representing perhaps the last benefits it will see under the nuclear deal.

Iran had hoped the lifting of sanctions would allow it to replace its aging commercial airline fleet, but the U.S. withdrawal has halted billion-dollar deals struck with Airbus and Boeing. European countries, along with Russia and China, remain committed to the nuclear deal, but European companies are unlikely to risk U.S. sanctions to do business with Iran.

The U.S. has been pushing its allies to halt their import of Iranian oil ahead of the November deadline. Among the top importers of Iranian oil are China, India, Turkey and South Korea.

Rouhani has suggested Iran might block the Strait of Hormuz in response to a shutdown of its oil exports. The strait at the mouth of the Persian Gulf is crucial to global energy supplies as about a third of all oil traded at sea passes through it.

Iran's navy and its paramilitary Revolutionary Guard routinely conduct seaborne exercises in the Gulf and the strait. U.S. officials last week said Iran carried out a similar exercise, though Tehran did not immediately acknowledge it.

The Associated Press contributed to this report.