Iran struck infrastructure in the Gulf on Saturday and threatened a "full-scale offensive" in retaliation for a week of intensifying US strikes on the Islamic republic.
A month after the foes agreed a now abandoned preliminary deal aimed at ending their war, renewed fighting has taken in a broader ranges of targets, with Tehran accusing Washington of hitting an airport, railway station and bridges.
Iran retaliated Saturday with strikes on an oil facility in Kuwait as well as a power and water plant, authorities in the Gulf state said, while in Bahrain the army said air defences repelled a wave of Iranian attacks.
"Iran will no longer limit itself to retaliatory, like-for-like responses... and no political border will be safe," said Major General Mohsen Rezaei, a senior military adviser to Iran's supreme leader, according to state media.
He said Tehran would resume "full-scale offensive operations" if US strikes continued in the coming days.
Kuwait accused Iran of targeting civilian sites and vital infrastructure after the strike on the power plant forced several electricity generation units to be deactivated. It was the second attack on a Kuwaiti power and water plant in as many days.
Kuwait's state oil firm reported injuries and damage in an attack on an oil facility, and the country's fire service said firefighters were injured battling blazes sparked by Iranian attacks.
Concerns that the renewed hostilities might drag on were spreading in the small Gulf state.
"The demand for water and canned goods has increased since this morning amid fears that services or supply chains will be affected," Kuwait resident Hassan Rayan, 61, said Saturday.
Fellow resident Ali Mahmoud, 46, noted that "the streets and beaches were almost empty, even though it is a holiday".
'War crimes'
In Bahrain, another US ally in the Gulf, the Iranian army said it targeted an air base used by the United States, according to the state broadcaster.
Jordan was also hit, with the Iranian state broadcaster reporting fuel tanks at its Al-Azraq base were targeted.
The Jordanian army said it had shot down 10 missiles, with no casualties or damage.
The secretary general of the Gulf Cooperation Council, Jasem Mohamed Albudaiwi, condemned the latest attacks, saying they constituted "war crimes requiring international accountability and prosecution, given the deliberate targeting of infrastructure and civilian facilities".
Hope for a political settlement to the war has fallen by the wayside, though mediators have attempted to bring both sides back to the negotiating table.
US President Donald Trump this week threatened to hit Iranian infrastructure, although there has been no confirmation from Washington since then that US forces have begun to do so.
Deputy Iranian foreign minister Kazem Gharibabadi told state TV on Saturday that Washington was "not getting anywhere with these aggressive actions, and in fact, if they are wise, they should choose other solutions".
"America has violated and stopped all its commitments under that memorandum of understanding, and we have also stopped all our commitments," he added.
Iranian state news agency IRNA reported Saturday that US attacks killed three people and wounded eight in the southern province of Hormozgan.
Local authorities said 116 telecommunications towers had been knocked out of service, with landline, mobile and internet connections down in some northern areas of the province.
In Khuzestan province, the deputy provincial governor said the US had attacked 95 locations in 12 cities over the past 10 days, according to Iran's Tasnim news agency.
Eight people had been killed in the attacks, he said.
Iran also said the supply of drinking water to several villages in the south had been cut off, accusing the US of striking power facilities and desalination plants in the village of Bonji, according to Tasnim.
Iran's energy ministry urged citizens to reduce electricity use and switch off air conditioners in peak hours after the power grid came under strain.
The health ministry said Friday that 50 people had been killed since the renewed fighting broke out and more than 500 injured.
'Capitulation'
David Khalfa, a Middle East specialist at the Paris-based Jean-Jaures Foundation, said a "widening range of strategic infrastructure" was being drawn into the conflict.
"The paradox is that, while the conflict continues to escalate, neither side has a strategic interest in allowing this dynamic to continue. Yet both perceive any compromise as a form of capitulation," Khalfa told AFP.
The latest bout of violence was sparked by Iranian attacks on ships in the strategic Strait of Hormuz, a vital transport lane for Gulf energy exports that Iran seeks to control.
Iran closed the strait after the war broke out in late February with US-Israeli strikes, and control over the route has become leverage in negotiations with the US, which recently reimposed its own blockade of Iran's ports.