A woman walks by a mural depicting Iran's late Supreme Leader Ayatollah Ali Khamenei. [Photo Credit: Reuters]

U.S. Treasury chief Scott Bessent said the United States will impose “the toughest sanctions in history” on Iran, a move he suggested would lessen the need for new major military operations.

Bessent’s ​comments on Thursday followed President Donald Trump’s threat a day earlier of “Economic Warfare” and warning of economic consequences against any country that provided “any type ‌of lifeline to Iran.” Bessent promised details next week.

Oil prices rose to more than a three-week high on Thursday following those U.S. threats of financial penalties aimed at forcing an end to a nearly six-month-old war that has stranded millions of barrels of Middle Eastern oil.

“I’m not sure why oil has popped up on this,” Bessent told CNBC. “If we are doing the maximum economic pressure, then that ​means that likely there will not be a large-scale kinetic restart,” he said, using a term referring to military force.

Thousands have been killed in the conflict, ​which drew in Gulf nations and shocked markets as Iran flexed its ability to curb shipping through the Strait of Hormuz — a ⁠waterway that carried about a fifth of all traded oil before February.

The U.S. and Iran have twice announced ceasefire deals, in April and June, aiming to restore the ​free flow of shipping through Hormuz on a path towards ending the conflict, but both quickly crumbled.

Iran has weathered near-continuous, punishing economic sanctions for nearly 50 ​years, since the Islamic Revolution of 1979.

Before Bessent spoke, Iran’s foreign ministry said it condemned U.S. economic and trade sanctions, calling them “economic terrorism” that would not “create even the slightest hesitation in Iranians’ determination to safeguard Iran’s independence, dignity and national sovereignty.”

Bessent told CNBC he would share more details on the latest package and “talk about exactly what we’re going to do” on Iran at a press conference on ​Monday.