As a deadline set by US President Donald Trump for a proposed agreement approached, Iranian civilians formed “human chains” around key infrastructure, local media reported.

The move followed Trump’s warning that the United States would completely destroy Iran’s power plants and bridges if negotiations failed. Iranian authorities urged citizens to gather at sensitive sites to deter potential strikes.

Iranian outlets, including Fars and Tasnim News Agency, reported crowds at major locations on Tuesday.

These included the northwestern city of Tabriz, Bisotun in Kermanshah Province, the Mazandaran power plant in the north, and the Shahid Rajaei Thermal Power Plant — the largest in Iran — located in Qazvin Province.

Photos and videos showed citizens holding national flags and placards reading, “Attacking power facilities is a war crime.” Many formed protective rings around installations, some holding hands.

Fars reported similar scenes in the southern city of Kazerun.

Footage showed adults encircling a power plant, with children also present. The agency said, “They gathered in front of the power plant to condemn attacks on public infrastructure, defining them as clear war crimes.”

Hundreds also formed dense human chains on bridges in Dehloran and Ahvaz in Khuzestan Province.

Earlier, Trump had declared that if the Strait of Hormuz was not opened by 8,00 p.m. (Eastern Time) on April 7, the US would bomb all of Iran’s power plants and bridges.

In response, Iran’s Minister of Youth Affairs and Sports, Ali Reza Rahimi, called for nationwide participation.

Speaking via state media on Monday, he said, “We invite all our youth, athletes, artists, students, university students, and professors. Regardless of belief or political inclination, we ask you to gather at 2.00 p.m. on Tuesday, around power plants — our national assets and the future of Iran and its youth.”

He described the mobilisation as “a human chain of Iranian youth for a bright tomorrow,” adding, “It will be a sign of the youth’s dedication to protecting Iran’s infrastructure and building a bright future.”

With less than a day to the deadline, reports emerged of attacks on transport infrastructure across the country.

Mehr News Agency, citing a source in Isfahan Province, reported that “the US and Israel attacked the Yahyaabad Railway Bridge in the Khorramabad region, killing two civilians and injuring three.”

A projectile also struck the Tabriz-Tehran highway, about 90 kilometres north of Tabriz in East Azerbaijan Province, halting traffic.

Further reports said bridges on the outskirts of Qom, railways in Qazvin, and rail lines in Karaj, west of Tehran, were bombed. Power outages were reported in parts of Karaj and Pardis.

Railway operations in Mashhad, in northeastern Iran, were fully suspended due to air raid alerts.