Iranian officials on Tuesday called on young people to form human chains to protect power plants, while US President Donald Trump warned that "an entire civilization will die tonight" if Tehran does not meet his latest deadline to agree to a deal that includes reopening the Strait of Hormuz.
Meanwhile, airstrikes hit two bridges and a train station in Iran, and the US struck military targets at the Iranian oil hub on Kharg Island. This attack marked the second time the island has been hit by US forces.
Trump has pushed back previous deadlines, but hinted that the one set for 8 p.m. in Washington was final, and rhetoric from both sides reached a peak, leaving the Iranians anxious.
Trump threatened to destroy all of Iran's power plants and bridges if Tehran does not allow full resumption of traffic in the strait, through which a fifth of the world's oil passes in peacetime. The Iranian president said 14 million people, including himself, have volunteered to fight.