Meanwhile, the warmongers in the Trump administration are effectively enablers for the most conservative elements in the very government they want gone. A powerful faction in the government in Iran justifies domestic oppression by referring to American bellicosity.

Trapped between the Trump administration and the local authoritarians are ordinary people. Amazingly, even under tremendous pressure, Iranian society has remained dynamic. In fact, the whole country is abuzz with peaceful struggle these days. Women are protesting against the mandatory head scarf, but this is just one example of dissent. On March 28 alone, Radio Zamaneh, an Amsterdam-based Persian-language radio station, reported five gatherings, rallies and strikes across the country over issues ranging from mass layoffs and the distribution of water to a pipeline being built through a town.

The recent phase of activism is impressively creative: Farmers in Isfahan Province have turned their backs on imams during Friday prayers in protest against the government; small-business owners in the town of Marivan rolled out a long stretch of empty tablecloths on the street to symbolize poverty. BBC Persian has estimated that about 17 protests and strikes per day are organized by labor unions and activists across the country.

More than it will hurt the government, Mr. Trump’s decision to abandon the nuclear deal will affect these grass-roots movements. It will damage political activism and peaceful, creative expressions of will to change.

For the working class and for low-income people, new sanctions and renewed isolation will mean fewer jobs, less security and more poverty. As a result, the poor will be forced to change their priorities: The time and energy they could dedicate to peaceful protests will be consumed by struggling to provide bread. Or things could take another turn: Extreme poverty may create such high levels of frustration that people turn to violence, eventually strengthening the hand of the oppressive state.

As for the middle class and people in large cities, renewed sanctions — especially alongside the talk of war — present an existential threat to the meager well-being they have worked so hard to cobble together. The Trump administration’s decision to pull out of the nuclear deal may well make the middle class more conservative, as they fear economic collapse and chaos, they will move closer to the government. They will give up demands for equality and justice in order to protect their hard-earned relative comfort.

As for the government itself, especially the faction intent on ruling with an iron fist, the sanctions will not hurt much. As the Obama years proved, sanctions never forced the Iranian government to cut back its security and military budgets. Instead, a choked-off economy and its accompanying black markets allowed a group of the powerful people to monopolize the economy, giving rise to a mafia-like class that funneled wealth to the top or transferred it overseas, and deployed all its political and military capital to protect it.

Those are the people who thrive under the sanctions. They are probably celebrating Mr. Trump’s decision.