U.S. Treasury Secretary Scott Bessent said on Sunday night that the Trump administration’s “economic D-Day” against Iran would begin at dawn, aimed at severing “every economic lifeline” sustaining the Islamic Republic.

Bessent described the campaign, announced by U.S. President Donald Trump last week, as “the single greatest financial offensive ever marshaled against an adversary,” saying the president had created the conditions to use every available federal agency and authority against Tehran. He also said that U.S. military action had destroyed nearly all of Iran’s military factories and buried its nuclear program.

The administration is expected to unveil new sanctions targeting Iran’s remaining sources of foreign trade, including countries that continue doing business with Tehran. Iran has warned countries against joining the U.S. campaign and threatened to further restrict oil exports through the Strait of Hormuz.

President Trump has dismantled Iran’s military capabilities, destroyed nearly 100 percent of its military factories, and buried its nuclear program.

We are now entering the endgame. At dawn begins an economic D-Day — the single greatest financial offensive ever marshaled against…

— Treasury Secretary Scott Bessent (@SecScottBessent) August 23, 2026

Iran warned on Saturday that countries joining the US economic campaign against Tehran will be treated as enemies.

“We declare to all countries ... do not join the economic war waged by the United States. Any country participating in the imposition of economic restrictions against us is considered an enemy,” Mohsen Rezaei, head of Iran’s Supreme National Security Council, told state television.

Trump on Sunday posted a graphic labeling the Strait of Hormuz “New U.S. Territory,” five days after posting the same image on Truth Social.

Trump previously said the United States had “total control” over the strategic waterway and suggested he would declare it U.S. territory after defeating Iran.

Iran is fighting a “full-scale economic, military and security war,” but remains steadfast in its defiance, President Masoud Pezeshkian said on Sunday.

Speaking at a ceremony pledging loyalty to the ideals of Islamic Republic founder Ayatollah Ruhollah Khomeini, Pezeshkian said, “The enemies imagined that with their pressure and actions Iran would collapse. Not only did this not happen, but the power and unity of the Iranian nation amazed the world,” according to the government-sponsored Mehr News Agency.

On Aug. 19, Trump announced the coming “economic D-Day” campaign.

The Iranian “navy is gone, their air force is destroyed, their military factories are now rubble, their currency is worthless and their country is hanging by a thread,” he wrote on Truth Social.

No one has given the Iranian regime a better chance to make a deal than he, Trump wrote.

“Tragically, for them, they have failed to take it. Therefore, today, I am announcing the most crushing economic operation ever taken against any country,” he continued.

The president threatened “tremendous economic consequences” for any country that lets its “financial institutions, businesses, airports or government entities to provide any type of lifeline to Iran.

“Oil smuggling, swap lines, cash transfers, exchange houses, ship registries, front companies—it all needs to stop now,” he stated. “You know who you are. This will be an economic D-Day.”

He called on all U.S. allies to “isolate and defeat the Iran threat.

“These maniacs are on the ropes,” he said. “These historic measures will cripple them and their ability to project terror worldwide. Iran will never have a nuclear weapon.”