Iranians once shrugged off Trump’s bluster. Now they’re worried.

In classrooms, taxis, hair salons and homes, many people in this nation of 80 million have gone from first dismissing Mr. Trump’s comments as political bombast to worrying about new sanctions and even military strikes by the United States. Iran’s supreme leader, Ayatollah Ali Khamenei, has responded to Mr. Trump with mocking sarcasm.

“Trump is unpredictable; our leaders are unpredictable,” Ms. Sameni said. “It suddenly feels as if we are on a sinking ship.”…

Some middle-class Iranians, who get their news from the approximately 150 illegal Persian-language satellite channels that broadcast from overseas into Iran, started contending that Mr. Trump could actually be a blessing. His perceived friendliness toward Russia has long been seen as a plus in Iran, with many people expecting Russia’s president, Vladimir V. Putin, to rein in Mr. Trump’s anti-Iranian stances.

“But we cannot trust the Russians to do so,” said Housang Tale, a historian who is critical of Russia’s relationship with Iran’s leaders. “They have used us throughout history, taken our land and sold us out,” he said of Russia. “Who says they won’t trade Iran with the U.S. for the Ukraine? More pressure is coming.”