The United States began rolling out Monday what Treasury Secretary Scott Bessent has called “the single greatest financial offensive ever marshaled against an adversary,” targeting Iran’s remaining economic lifelines starting at dawn.

In a statement and an opinion piece published in the Financial Times, Bessent declared that after President Donald Trump’s military campaign dismantled much of 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. Our objective is to sever every economic lifeline that sustains the tyrannical regime until Tehran stands alone.” — Scott Bessent, U.S. Treasury Secretary

The campaign will target Iranian oil sales, financial transactions, and any support flowing from third countries. Nations, banks, shipping firms, and other entities that continue doing business with Tehran now face designation as global pariahs, with secondary sanctions and the full weight of U.S. Treasury enforcement power expected to follow.

Bessent emphasized that President Trump has created the conditions “to leverage every agency, every authority and action many assumed we would never summon.” He added a pointed warning aimed at governments still weighing continued ties with Tehran.

“Those who fear the danger of defying Tehran ought not to discount the cost of testing Washington.” — Scott Bessent

Tehran Answers With a Threat of Its Own

Iran has responded sharply. A senior official stated that any country joining or supporting the U.S. economic effort would be regarded as committing an act of war. Tehran went further, threatening to halt all oil exports from the Persian Gulf — including through the Strait of Hormuz — if the pressure campaign continues, raising the prospect of major disruption to global energy markets.

From Battlefield to Balance Sheet

Analysts describe the move as a deliberate strategic pivot — from military operations to total economic isolation. Markets are already bracing for potential oil-price volatility as governments and firms weigh the risks of continued ties with Iran against the costs of provoking Washington’s retaliation.

Bessent is expected to detail the full package of measures at a press conference later Monday. The offensive marks the latest escalation in the months-long U.S.-Iran conflict, with Washington betting that maximum financial pressure can force the regime’s collapse without a return to large-scale kinetic warfare.