President Trump on Thursday imposed major new sanctions on the Islamist terrorist group Hezbollah, as his administration continues its all-out economic squeeze on the Iranian regime that backs it.

After a speech punctuated by raucous applause, Trump signed the Hizballah International Financing Prevention Amendments Act (HIPAA) of 2018 into law on the 35th anniversary of Hezbollah's 1983 truck bombing of the barracks in Beirut, Lebanon, which killed 241 U.S. service members and 58 French peacekeepers.

“It was the single deadliest day for the Marines since Iwo Jima," Trump said in a ceremony at the East Room of the White House. "The attack was carried out by Hezbollah, which Iran was instrumental in founding earlier to advance its radical agenda and remains its main patron today. And we're doing a big number on Iran today, in case you haven't noticed."

The military members and veterans in attendance, whom Trump called "spirited" at the beginning of his remarks, burst into whistling and applause. He was joined by Defense Secretary James Mattis, Chief of Staff John Kelly and survivors of the 1983 attack.

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In August, the Trump administration restored sanctions against Iran that had been suspended under former President Barack Obama's 2015 nuclear deal. Trump has long characterized that deal as an ineffective giveaway that allowed Iran to finance terrorism without actually checking its nuclear ambitions.

"We are doing a big number on Iran today, in case you haven't noticed." — President Trump

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 already imposed target Iranian trade in automobiles, gold and other key metals.

On Thursday, the president highlighted Iran's economic woes, as the country moves to take emergency measures to placate an increasingly discontent populace.

Soaring unemployment and poverty prompted demonstrators to torch police vehicles and burn tires in August, when 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.

“They are rioting in their streets, their money has collapsed, their lives are a lot different," Trump said Thursday. “I’ll tell you what, they are not the same country they were when I took office.”

He added: "They're not looking so much for the Mediterranean. When I took office they were looking for the Mediterranean. They were going to take over everything. Now they want to survive. Whole different deal, folks."

According to the International Monetary Fund, Iran's economy is set to shrink by 3.6 percent next year. Before Trump withdrew from the nuclear deal, the IMF had expected growth in excess of 4 percent.

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The value of Iran's rial currency has also plummeted amid staggering 30 percent inflation and a rapidly increasing cost of living, with 140,000 rials required now to purchase a single U.S. dollar -- up from 40,000 in January.

In September, National Security Adviser John Bolton delivered a stern warning to Iran at a major summit in New York, telling the regime that "we are watching, and we will come after you" and that there will be "hell to pay" if it continues on its current course.

Trump, in a separate address to the United Nations last month, called on allied nations to "isolate" Iran and crack down on companies seeking to bypass sanctions against the regime.

For his part, Iranian Supreme Leader Ayatollah Ali Khamenei has claimed that an attack last month at an Iranian military parade, which left dozens of Iranian military personnel dead, was carried out by militants trained by Israel and the Gulf states, and supported by the U.S.

Thursday's sanctions bill marks the continuation of the Trump administration's effort to target Hezbollah specifically. In February, senior White House officials instituted what they called at the time the "first wave" of sanctions against Hezbollah as a means of pressuring Iran.

The Treasury announced that it was sanctioning a network of companies and individuals in Lebanon, Sierra Leone, Ghana, Liberia and other countries linked to Hezbollah financier Adham Tabaja.

“It is Iran’s primary proxy used to undermine legitimate Arab governments across the Middle East," Treasury Secretary Steven Mnuchin said in a statement earlier this year. "The administration is determined to expose and disrupt Hezballah’s networks, including those across the Middle East and West Africa, used to fund their illicit operations."

And in May, the U.S. imposed sanctions on two top Hezbollah leaders.

"Over the past year we have levied the highest sanctions ever imposed on Hezbollah -- in a single year, by far," Trump said Thursday. "Just a few moments ago, I signed legislation imposing even more hard-hitting sanctions on Hezbollah to further starve them of their funds. And they are starving for them."

Earlier this month, Secretary of State Mike Pompeo announced that the U.S. is terminating a 1955 treaty with Iran, after the United Nations' top court used that treaty to order the U.S. to ease some of its sanctions on the regime.

The U.S. has designated Hezbollah a terrorist organization that also plays a major political role in Lebanon. The bill Trump signed Thursday also expands the list of those who can be sanctioned for doing business with Hezbollah.

“No terrorist group other than Al Qaeda has more American blood on its hands," Trump said in Thursday's remarks.

Fox News' Adam Shaw and The Associated Press contributed to this report.