The US and Israel have traded air strikes with Iran's military across the Middle East as the besieged Tehran government warned its state security forces are ready with "fingers on the trigger" to confront any revival of anti-government protests.
Following an exchange of some of the heaviest bombardments in the region yet, the combatants renewed their attacks on opposing targets in Israel, Lebanon and the Gulf early on Wednesday as the war stretched into its 12th day.
The conflict has effectively blocked vital shipping lanes through the Strait of Hormuz, halting the flow of one-fifth of the world's fossil energy supplies from the petroleum-rich Gulf.
But after a major surge in crude oil prices on Monday, global energy prices have tumbled and stock markets rebounded as investors bet that US President Trump would seek to end the war soon.
Nevertheless, Iran's Islamic Revolutionary Guard Corps vowed to block oil shipments from the Gulf unless US and Israeli attacks ceased.
The Revolutionary Guards said it fired missiles on Tuesday evening at Qatar's US-run Al Udeid base and the Al Harir base in Iraq's Kurdistan, followed by drone attacks on a gathering of US troops at Al Dhafra air base in the United Arab Emirates and Juffair naval base in Bahrain.
Early on Wednesday, Iranian state media reported another round of attacks was unleashed on US military installations in Bahrain.
A drone struck a major US diplomatic facility in Iraq on Tuesday but there were no injuries and everyone was accounted for, according to a US official and an internal State Department alert.
Overnight into Wednesday morning, millions of Israelis were repeatedly driven into bomb shelters as the military warned Iran had launched missiles toward Israel, a sign that Tehran retains the capacity to strike Israel after nearly two weeks of hostilities.
There was no immediate word of whether any of the missiles reached the ground.
The latest attacks from Iran roughly coincided with a new Israeli barrage on Beirut aimed at rooting out the Iran-backed group Hezbollah, which has fired into Israel from Lebanon in solidarity with the Tehran government.
The night before, Tehran residents reached by Reuters described what they called the war's most intense night of bombardment.
"It was like hell. They were bombing everywhere, every part of Tehran," a resident said by phone, speaking on condition of anonymity for security reasons.
"My children are afraid to sleep now."
There has been little sign of anti-government protest in Tehran during the war, and Iran moved to clamp down further on internal dissent days after Trump exhorted Iranian citizens to seize an opportunity afforded by US and Israeli attacks to rise up and overthrow their government.
Fearing a revival of anti-government demonstrations, Iran's police chief Ahmadreza Radan warned that "anyone taking into streets at the enemy's request will be confronted as an enemy not protester".
"All our security forces have their fingers on the trigger," Radan told state television.
Iran also arrested dozens of people, including a foreign national, accused of spying for the country's "enemies", the Intelligence Ministry said on Tuesday.
The White House on Tuesday reiterated Trump's threat to hit Iran hard over moves by Tehran to stop the flow of energy supplies through the Strait of Hormuz.
The US Central Command said the 16 Iranian mine-laying vessels had been eliminated near the strait on Tuesday.
More than 1300 Iranian civilians have been killed since the US and Israeli air strikes began on February 28, according to Iran's UN ambassador, Amir Saeid Iravani.
He said nearly 8000 homes have been destroyed, along with 1600 "commercial and service centres" and dozens of medical, educational and energy-supply facilities.
Scores have also been killed in Israeli attacks on Lebanon, while Iranian strikes on Israel have killed at least 11 people.
Iran has struck US military bases and diplomatic missions in Arab Gulf states but also hit hotels, closed airports and damaged oil infrastructure.
In addition to seven US soldiers killed in the conflict, the Pentagon on Tuesday estimated about 140 American troops have been wounded.