DUBAI, United Arab Emirates (AP) — Iran’s currency sank to an unprecedented low Monday as Washington prepared to unveil new sanctions described as an “economic D-Day,” intensifying pressure on an economy already damaged by earlier restrictions and a U.S. naval blockade.

The rial fell to 2.02 million against the U.S. dollar when trading began on unofficial currency markets. Iran’s Central Bank maintained an official rate of roughly 1.5 million rials per dollar, although most Iranians rely on the informal market rate.

The currency was already struggling before the United States and Israel attacked Iran on Feb. 28, amid double-digit inflation and economic contraction. It has since repeatedly reached new lows as almost six months of conflict have caused further damage.

Even so, U.S. President Donald Trump has failed to secure concessions from Tehran, which continues to tightly control shipping through the Strait of Hormuz. Before the war, about one-fifth of globally traded oil passed freely through the strategic waterway, but Iranian strikes and threats have sharply restricted traffic during the conflict.

Iran and Oman, located across the strait, are reportedly close to completing an agreement for jointly managing the passage. Regional officials have said the proposal would require vessels to enter the Persian Gulf along an Iranian-controlled channel and leave through a route overseen by Oman.

Trump has strongly criticized Oman, despite its status as a U.S. ally, and threatened to bomb the country if it “gets in the way.”

Oman’s foreign minister was scheduled to travel to Iran on Tuesday for another round of discussions.

Seeking to end the deadlock with Tehran, U.S. Treasury Secretary Scott Bessent said even tougher sanctions would be announced Monday. The measures were expected to include secondary penalties targeting countries that continue conducting business with Iran.

“President Trump has devastated Iran’s economy, leaving the rial weaker than ever and inflation near historic highs,” Bessent wrote Sunday in an opinion article. “The government’s last shelter is the mistaken belief among fearful countries that tolerating aggression can produce lasting peace.”

The United Arab Emirates had already announced the previous week that it was halting all trade with Iran. Trump spoke by telephone with UAE leader Sheikh Mohammed bin Zayed Al Nahyan one day before the decision was made public.

The UAE has for years ranked among Iran’s most important commercial partners and has been its largest source of imports. It has also served as a significant re-export center and financial base for Iranian companies.

After Bessent’s comments, Mohsen Rezaei, the hard-line head of Iran’s Supreme National Security Council, said in a social media post that support by any country for new U.S. economic measures would be regarded as an “act of war.”