The U.S. is preparing to deal another major blow to Iran. This time, the Trump administration is aiming to hit Tehran where it believes will hurt most-Iran's coffers.

Treasury Secretary Scott Bessent is scheduled to unveil additional categories of Iran-related conduct subject to secondary sanctions at 1 p.m. Monday, according to a source familiar with the announcement.

Bessent referred to the impending measures as "an economic D-day" in the Financial Times on Sunday. They will amount to "the single greatest financial offensive ever marshaled against an adversary," he said.

The new sanctions will be layered on top of decades-old U.S. sanctions. Iran has kept its economy afloat by skirting those sanctions and forging trade ties with China, India, Iraq, Pakistan, Turkey, and the United Arab Emirates. The U.S. had temporarily rolled back some of those sanctions under the memorandum of understanding signed in June between both countries.

But with his announcement today, Bessent seeks to isolate Iran further and push its fragile economy over the edge.

Iran's economy has been in a tough spot predating U.S. strikes in February. Economic discontent was one of the main drivers of a wave of antiregime protests between December and January. Recent measures, including the U.S. naval blockade in the Strait of Hormuz, have tightened financial conditions further. The Iranian rial hit a record low against the U.S. dollar on Monday ahead of Bessent's announcement.

Iranian leadership appears divided on how to address the country's economic hardships. On Saturday, Iranian President Masoud Pezeshkian pushed for the U.S. and Iran to recommit to their MOU.

"One cannot continue with war forever," he said.

Hard-liners, however, are holding out. Foreign Ministry spokesperson Esmaeil Baqaei said on Monday that Iran "will not allow the war to end on the terms of the aggressor."

Other Iranian officials threatened an economic campaign against countries assisting any new U.S. sanctions.

"If the economic war continues, not a single drop of oil will be exported? neither through the Strait of Hormuz nor from anywhere in the Persian Gulf," Mohsen Rezaei, secretary of Iran's Supreme National Security Council, wrote on X on Sunday. "Iran will regard any country's participation in or support for America's economic war against the Iranian people as an act of war."

These threats could make it challenging for Tehran's trading partners to cut ties, diluting the impact of U.S. sanctions, according to analysts at Oxford Analytica.

"Regional neighbors will still struggle to unwind all linkages, whether because of Iranian threats or the impact on their own interconnected economies," the analysts wrote in a note Monday.

Russia and China are also likely to push back on the measures, opening the administration to a new host of problems.

"Bessent can't credibly punish anyone throwing Iran a lifeline without hitting China hard, which risks the tacit 20% tariff cap that keeps rare earths flowing and the Sept. 24 Xi visit Trump is widely viewed as not wanting to derail," Henrietta Treyz, director of economic policy at Veda Partners, wrote in a note Monday.

Iran has another advantage that could help them hold out against economic pressure a bit longer: the looming U.S. midterm elections. Polls show Iran war is unpopular with voters, increasing pressure for the Trump administration to wrap up operations before people take to the voting booths.