President Donald Trump on Thursday threatened to leave "nothing left" in Iran after US-Israeli forces widened their attacks against civilian infrastructure across the country.
Airstrikes caused widespread destruction at Iran's most important medical research facility while the country's largest bridge was destroyed.
"The biggest bridge comes tumbling down, never to be used again – much more to follow!" Trump declared on Truth Social.
"Our military … hasn’t even started destroying what’s left in Iran. Bridges next, then electric power plants!" he wrote in a subsequent post.
Iran's Revolutionary Guard responded by threatening to destroy critical bridges in neighbouring Arab states, continuing its pattern of matching Israel and the US's escalation.
Fresh attacks on Gulf oil and gas infrastructure were reported overnight. A drone attack triggered a blaze at a major oil refinery in Kuwait while a gas complex near Abu Dhabi suspended operations after an intercepted projectile caused a fire. Kuwaiti authorities said a power and water desalination plant had incurred damage.
The rhetoric coming out of Trump administration has taken a more extreme turn this week, signifying growing frustration by Iran's refusal to agree to its maximalist demands.
The US president used a primetime national address on Wednesday to threaten to bomb the country "back to the Stone Age" and repeated warnings that power plants could soon come under attack.
Iran issued a defiant response, with Foreign Minister Abbas Araghchi saying the destruction of civilian infrastructure "will not compel Iranians to surrender".
The country's leadership swiftly rejected a US ultimatum to surrender to its pre-war demands and vowed to maintain its stranglehold over the Strait of Hormuz. The effective closure of the strategic chokepoint has triggered one of the largest global energy crises in history, further souring the American public's mood on the Trump presidency and increasing the chances of a Democratic landslide in this year's mid-term elections.
The Trump administration has responded to the growing economic and political fallout by upping the civilian cost of the war, culminating in yesterday's attacks on the historic Pasteur Institute and the destruction of the B1 bridge.
A spokesperson for Iran's health ministry condemned the attack on the institute as a "direct assault on international health security" and urged global health bodies to intervene. The Pasteur Institute has led the country's public health research for more than a century and pioneered the developed of indigenous vaccines for diseases such as smallpox and Covid-19.
The bridge, which links Tehran to the western city of Karaj, was set to become a key commuter route out of the capital.
The attacks suggest that the punishing aerial campaign is becoming increasingly indiscriminate, with the US and Israeli air forces attacking infrastructure that appears to have no clear military purpose.
Strikes have forced Iran's two largest steel plants to shut down while health facilities, pharmaceutical sites and universities have been bombed.
Iran's Red Crescent Society says that US-Israeli forces have destroyed or damaged more than 300 hospitals and medical facilities and more than 90,000 homes during the war.
More than 100 US-based international legal experts said this week that the US military is committing serious violations of international law in Iran and warned of possible war crimes.
Iran has responded by escalating its strikes across the Gulf, targeting energy facilities, aluminium plants and US companies.