DUBAI, United Arab Emirates (AP) — With U.S. President Donald Trump’s deadline rapidly approaching for Iran to reopen the Strait of Hormuz or face the massive bombing of the country’s infrastructure, Iran on Tuesday urged youths to form human chains around power plants and its president said 14 million people had answered calls to volunteer to fight.

Trump has threatened to bomb all of Iran’s power plants and bridges if Iran does not meet his Tuesday 8 p.m. EDT deadline to allow shipping traffic to fully resume through the strategic waterway, through which a fifth of the world’s oil transits in peacetime.

“The entire country can be taken out in one night,” Trump said. Trump has repeatedly extended previous deadlines, but suggested this one was final, saying he’d already given Iran enough extra time.

Well before the deadline, renewed American and Israeli airstrikes hit targets across the country, killing nearly three dozen people.

Israel’s military said it had attacked a Iranian petrochemical site in Shiraz, the second day in a row it had hit such a facility after striking an offshore plant at the South Pars natural gas field. Israel also issued a Farsi-language warning telling Iranians to avoid trains, throughout the day, likely telegraphing intended strikes on the rail network.

Another strike hit the Khorramabad International Airport in western Iran, and a strike on an unidentified target in Alborz province, northwest of Tehran, killed 18 people, according to state media.

Iran choked off shipping through the Strait of Hormuz after Israel and the U.S. attacked on Feb. 28, starting the war. It has already rejected a 45-day ceasefire proposal and said it wants a permanent end to the war.