“Leave Iran now,” the US authorities warned, advising citizens to plan departures independently without expecting assistance from the US government.

For those unable to leave immediately, they recommended finding a secure location in their residence or another safe building.

The advisory also warned of ongoing internet outages and urged Americans to plan alternative means of communication.

It suggested that, if safe, citizens could consider leaving Iran overland via Armenia or Türkiye.

US-Iranian dual nationals were reminded that Iran does not recognise dual citizenship.

The US authorities cautioned that dual citizens must exit the country using Iranian passports, as showing a US passport or any ties to the United States could result in detention by Iranian authorities.

The alert comes amid growing US-Iran tensions. On Monday, US President Donald Trump imposed a 25% tariff on any country doing business with Iran.

Trump has repeatedly warned that the US could take action if Iranian authorities use lethal force, while also expressing openness to diplomatic solutions.

According to reports, the president was briefed on a range of military and covert options, including cyber operations and psychological campaigns targeting Iranian communications and state media.

Officials told CBS News that these measures could be deployed separately or simultaneously, but no final decision has been made.

The White House is expected to review updated Iran options on Tuesday.