Iran has taken too long to negotiate a deal and will now "have to pay the price", President Donald Trump says, while Tehran is reassessing diplomatic engagement with Washington after tit-for-tat strikes.
Iran launched missile and drone attacks on US bases in Jordan, Kuwait and Bahrain in retaliation for American strikes on Iranian targets around the Strait of Hormuz.
The exchange of fire, which came after Trump said Iran had downed a US Apache helicopter near the strait, marks one of the most significant escalations since Washington and Tehran agreed to a ceasefire in April.
"Iran is all talk and no action," Trump said in a social media post on Wednesday.
"They've taken too long to negotiate a deal that would have been great for them, now they will have to pay the price!!!"
The US military said it had targeted Iranian air defences, ground control stations and surveillance radar sites in what it described as a "proportional response" to the downing of the helicopter, whose two crew members were rescued.
Iran's Gulf neighbours and Jordan activated air defences to intercept incoming missiles and there were no immediate reports of damage to US bases.
The escalation - just days after Iran exchanged strikes with Israel for the first time since the ceasefire - cast fresh doubt on prospects for a deal to end the war, which began on February 28 with joint US-Israeli strikes on Iran.
Iran's foreign ministry said Tehran would "reassess" its diplomatic engagement with Washington after what it called repeated ceasefire violations.
"Any diplomatic process requires a minimum stable environment," spokesman Esmaeil Baghaei said.
The US strikes lasted about four hours early on Wednesday, and a US official said almost 20 Iranian targets were hit.
Iran's Islamic Revolutionary Guard Corps (IRGC) said Qeshm Island and the port of Sirik were attacked.
Iranian media also reported explosions in Bandar Abbas, another port city, and later near Jask at the entrance to the Strait of Hormuz.
with dpa