US Central Command said in a statement on Tuesday evening it had completed the latest barrage against Iranian military targets including air defence sites, radar systems and maritime assets.
The US strikes followed others on Sunday that ended a month without military action and threatened to fully reignite a conflict that has spiked global oil prices and posed political problems for Republicans in November's midterm congressional elections.
The renewed fighting comes after President Donald Trump had appeared to pivot toward trying to bend Iran to his will through economic sanctions.
"If the failed Nation of Iran retaliates for this very justified attack, they will be hit again at a much harder and higher level, but it will not be the biggest attack of them all, that is waiting in the wings," Trump warned on social media.
US Central Command said the latest strikes were in response to Tehran trying to attack commercial ships and American forces in the Middle East. Trump offered an additional explanation, telling Fox News in a phone call that US forces struck Iran's radars.
"They tried to rebuild their radar because they can't see anything," Trump told Fox.
"We waited until it was almost built and then we hit it."
After the US attacks started, Iran launched ballistic missiles at Jordan. The Iranian Revolutionary Guard claimed to have targeted a US base along Jordan's Gulf of Aqaba coast, according to Iran's state television.
Jordan's military said it shot down 10 of the missiles and the three remaining landed in unpopulated areas. Explosions that appeared to be interceptions of incoming air attacks were seen over Aqaba.
Iranian state media reported that the US had bombed civilian sites along Iran's southern coast and hit a civilian airport.
A US strike hit a home where a wedding ceremony was being held in Kuhestak in southern Iran, killing five people, including a child, and wounding at least 68 others, Ahmad Nafisi, Hormozgan Province's deputy governor, told Iranian state television in a phone call.
"Make no mistake: these crimes will not go unpunished," Ebrahim Azizi, chairman of the Iranian parliament's National Security and Foreign Policy Committee, said on X.
US Central Command is aware of the reports of civilian casualties, said Captain Tim Hawkins, a spokesman. He noted that they "originated from Iranian state media".
"The US military never targets civilians, unlike the IRGC," Hawkins said.
The Kuwaiti Army said on X that its air defences intercepted drone attacks "following the criminal Iranian aggression". Iran also said it launched a drone attack at US forces in Bahrain.
Iran said the armed forces would deliver what they described as "crushing and devastating blows" against the United States.
The state-run IRNA news agency cited a statement by Iran's paramilitary Revolutionary Guard, which warned that the attacks have only strengthened the Islamic Republic's resolve and tightened Iran's effective closure of the Strait of Hormuz.
Explosions were reported across several southern Iranian coastal areas, including the port city of Bandar Abbas that is home to naval and air force facilities as well as Qeshm Island in the Strait of Hormuz.
Iranian state television said US strikes hit a fishmeal factory on Qeshm Island and several civilian sites in Hormozgan province as well as the civilian Jiroft Airport in central Iran's Kerman province, saying a projectile struck an area outside the runway and caused no casualties or damage to airport infrastructure.
Tavanir, Iran's electricity grid management company, said several parts of Hormozgan province's power network had been struck.
The US and Iran are both seeking control over the Strait of Hormuz, a narrow waterway off Iran's coast that is a vital oil shipping corridor. Tehran effectively closed it after the war began.
Oil prices have moved sharply higher this week with renewed clashes between Iran and the United States. Crude, already up about seven per cent this week, continued to rise following the strikes on Tuesday.
The price of crude has jumped more than 50 per cent this year and it's dragged the cost of gasoline upward with it.
Before military action began again, the Trump administration had argued that hitting the right economic target in a campaign of financial isolation would get Tehran to its breaking point.
Now, strikes are renewing even as US stockpiles of advanced interceptors have been diminishing and the war has been unpopular among many Americans.
A return to open conflict would be dangerous for the region, where Iran has targeted US military bases and infrastructure in Gulf countries since the war began.
