The United States expanded its air strike campaign against Iran early Friday by hitting more bridges and apparently collapsing a tower at a key Iranian port, part of US President Donald Trump's threats to start striking infrastructure to pressure Tehran to ease its chokehold on the Strait of Hormuz. Iran launched new missile attacks against US-allied nations in the Middle East, including Qatar, a key mediator in the war.The interim ceasefire agreed to last month has collapsed, and the region has endured days of back-and-forth attacks by the US and Iran as they battle for control of the strait. Iranian officials say US strikes have killed more than 35 people and wounded over 300 others, with new casualties reported in Friday's strikes.When the US and Israel launched the war on Iran on February 28, Tehran effectively closed the strait to shipping traffic, a move that sent the price of oil soaring and gave Iran major leverage in negotiations.Speaking in a prime-time address to the American public, Mr Trump insisted the war was going well."We are likewise winning big in Iran, and you will see the fruits of that labour very, very shortly," Mr Trump said.Bridges and port tower hit in IranThe US air strikes hit bridges overnight into Friday in Iran's southern Hormozgan province, killing at least seven people, Iranian state television reported. The attacks hit Bandar Khamir, a city on Iran's coast on the Strait of Hormuz.The US military's Central Command said it hit dozens of targets in its latest air strikes, which concluded at dawn Friday, the sixth night in a row of American attacks.The strikes also appeared to have collapsed a tower at Iran's Chabahar port on the Gulf of Oman, a key trade route for landlocked neighbouring Afghanistan.Chabahar port, which Iran had been running with support from India, has been a repeated target of American air strikes. Iranian state media acknowledged a third round of strikes on the facility without immediately acknowledging the tower's collapse.Smoke rises during what the US military says is its latest wave of strikes on Iran. (Reuters: US Central Command/Handout)Iran described the tower as overseeing commercial traffic into the port.However, Iran's paramilitary Revolutionary Guard also operates at ports across the country.Iran retaliates by targeting Qatar, a mediator in the warOn Friday, Qatar twice warned the public to take shelter as a barrage of Iranian missiles targeted the nation. People heard explosions overhead as air defences fired to intercept the missiles. Qatar's Interior Ministry said falling debris wounded a child.Qatar is a key mediator with Pakistan in trying to reach an end to the Middle East conflict.But talks have broken down over Iran's chokehold on the Strait of Hormuz.Iran earlier targeted Bahrain and Kuwait over US air strikes hitting bridges in the Islamic Republic overnight.AP