The United States is preparing what Treasury Secretary Scott Bessent described as the “toughest sanctions in history” against Iran, as the Trump administration intensifies economic pressure on Tehran and seeks to force an end to the nearly six-month-old conflict.

Bessent said the focus on economic measures could reduce the need for further major military operations against Iran. His remarks came a day after President Donald Trump threatened “Economic Warfare” and promised unprecedented economic isolation against Tehran.

Oil prices climbed to their highest level in more than three weeks following the US threats, with markets already under pressure from disruptions to Middle Eastern energy supplies and restrictions on shipping through the Strait of Hormuz.

“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, referring to military action.

Iran calls US sanctions ‘economic terrorism’

Iran condemned the planned sanctions, with its Foreign Ministry describing the US measures as “economic terrorism” that would hurt ordinary Iranians and amount to crimes against humanity.

Bessent said the United States would provide further details at a press conference on Monday.

“It is a one-two punch. We have the blockade, and we are going to have the toughest sanctions in history,” he said, referring to a US naval blockade imposed on Iran in April that was paused for a month in mid-June.

“It is going to work in Iran and we are going to collapse this regime. It is time for our allies and the rest of the world to make a decision,” Bessent said.

The conflict has killed thousands of people, drawn Gulf nations into the crisis and disrupted energy markets. Iran has demonstrated its ability to restrict shipping through the Strait of Hormuz, a crucial waterway that carried about a fifth of global oil traded before the conflict began.

The United States and Iran have announced ceasefire agreements twice, in April and June, with both aimed at restoring shipping through Hormuz and creating a path towards ending the conflict. Both agreements, however, quickly collapsed.

US warns China over Iran trade

Bessent also warned countries continuing commercial ties with Iran that they could face US action.

Asked whether Washington could target China for doing business with Tehran, Bessent said some discussions were better conducted privately.

“Keep in mind that the Chinese get 50% of their energy from inside the Gulf. So it would do them a big service to get with the programme,” he said.

China accounts for more than 80 per cent of Iran’s shipped oil purchases, according to 2025 data from analytics firm Kpler. However, further economic pressure on Beijing could trigger retaliation against Washington, given China’s importance as a major exporter to the United States, including of critical rare-earth minerals.

Iran has faced sanctions for decades

Trump said in a social media post on Wednesday that the United States would pursue “Economic Warfare and Isolation on an unprecedented scale” against Iran.

“ANY country that allows its financial institutions, businesses, airports, or government entities to provide any type of lifeline to Iran will itself face TREMENDOUS Economic Consequences,” Trump wrote.

Iran has lived under extensive US sanctions for decades, with economic restrictions dating back to the Islamic Revolution in 1979.

Iranian Foreign Minister Abbas Araqchi accused Trump of attempting to divert attention from economic problems in the United States, including high debt and rising interest rates.

He also criticised Washington’s continued use of sanctions, saying the policies would produce further failures and alienate the Iranian population.

“America’s economic terrorism threatens the global economy and the national sovereignty of countries around the world,” Araqchi said on X.

Trump’s Iran war objectives remain unresolved

Trump has yet to achieve the objectives he outlined at the beginning of the conflict, including dismantling Iran’s nuclear programme, reducing its ability to strike regional rivals and creating conditions for Iranians to challenge the country’s clerical leadership.

While Trump has repeatedly issued threats through social media, it remains unclear which specific measures will ultimately be implemented. The president has not identified individual countries that could face penalties, although his warning could affect US allies involved in efforts to mediate between Washington and Tehran.

Meanwhile, Iran has been negotiating with Oman over an agreement to manage traffic through the Strait of Hormuz. Tehran has said in recent weeks that the negotiations were nearing an agreement.

Trump responded to those talks on Monday by warning that he could bomb Oman, a longstanding US security partner, if the Gulf state “gets in the way”.

Omani Foreign Minister Badr Albusaidi, speaking after meeting his Japanese counterpart on Thursday, said lasting security in the Strait of Hormuz would require a permanent peace in the region and rejected further escalation.