An Iranian street money exchanger holds a U.S. dollar in downtown Tehran on July 30. Iran's currency has dropped to a record low ahead of the imposition of renewed American sanctions, with many fearing prolonged economic suffering or possible civil unrest. (Vahid Salemi/AP)

Secretary of State Mike Pompeo said Sunday that the United States will fully enforce sanctions against Iran, scheduled to be put back in place Monday.

“The United States is going to enforce these sanctions,” Pompeo told reporters returning with him from a summit in Southeast Asia. Asked about Tehran’s prospects for evading the prohibitions on financial transactions and eventually oil purchases from Iran, he said Iran will not succeed.

“It’s an important part of our efforts to push back against Iranian malign activity,” he said of the sanctions.

As part of a historic 2015 agreement between Iran and six world powers, including the United States, U.S. and international sanctions related to Iran’s nuclear activity were suspended once Tehran accepted technical limits on its program. By almost all accounts, the wide spectrum of U.S. and multilateral sanctions were responsible for getting Iran to the negotiating table.

But President Trump pulled the United States out of the agreement in May. The first round of financial sanctions should return Monday. And more punishing oil sanctions will return in November.

Iranian Foreign Minister Mohammad Javad Zarif attended the summit of Southeast Asian nations that just concluded. According to his taunting tweets, Zarif assiduously worked the room in Singapore, urging countries to continue doing business with Iran even after the resumption of U.S. sanctions.

Countries and businesses that go along, however, could be exposed to secondary U.S. sanctions. Mindful of the high cost, some foreign businesses that took advantage of the diplomatic breakthrough have begun winding down their operations in Iran.

Pompeo set a high bar for tensions to ease and trade to start flowing again. He said it will require “enormous change” by the Iranian government to break free of the U.S. sanctions yoke. He insisted that most diplomats at the Singapore summit agree with the United States.

“They’ve got to behave like a normal country,” he said of Iran. “That’s the ask. It’s pretty simple. We think that most other countries, everyone with whom I spoke, understands that they need to behave normally, and they understand that this is a country that threatens them.”

Calling the Iranian government a bunch of “bad actors,” Pompeo held out slim hope for its behavior to moderate and to negotiate over U.S. concerns such as its ballistic missile testing and its support for militants in the region.

“We’re happy to talk, if there’s an arrangement that is appropriate, that can lead to a good outcome,” Pompeo said. “Perhaps that will be the path the Iranians choose to go down. But there’s no evidence today of a change in their behavior.”

Referring to protests that have spread through Iran in recent months, Pompeo added, “The Iranian people are not happy — not with the Americans but with their own leadership. They’re unhappy with the failure of their own leadership to deliver the economic promises that their leadership promised them.”

Although Pompeo has consistently avoided calling directly for regime change, he has come close, and seemed to hint at it again Sunday.

“This is just about Iranians’ dissatisfaction with their own government,” he said. “And we want the Iranian people to have a strong voice in who their leadership will be.”