The first round of U.S. nuclear sanctions on Iran officially snapped back into place on Tuesday.
President Donald Trump tweeted early Tuesday announcing the reinstatement of the "most biting sanctions ever imposed." He also reiterated his earlier statements that anyone doing business with Iran won't be doing business with the U.S.
The sanctions affect Iran's trade in gold and other precious metals, its automotive sector and its purchases of U.S. dollars.
In 2015, France, the U.K., Germany, Russia, China, the U.S. and Iran signed the nuclear deal. It put restrictions on Iran's nuclear program in return for relief from economic sanctions.
Trump pulled the U.S. out of the agreement back in May. Since then, some of those world powers have been scrambling to keep the deal intact without the U.S.' participation.
Iran's economy has been suffering in recent months, sparking protests. The country's currency, the rial, has reportedly lost about half of its value since April.
The Washington Post reports Secretary of State Mike Pompeo said that the Iranian government would have to make an "enormous change" to get out of U.S. sanctions.
The White House says the next round of sanctions, which will affect Iran's oil industry and banks, is set to go into effect Nov. 5.