Iran has targeted US military sites across the Middle East in a "crushing response" to US strikes.
Early on Wednesday, US Central Command (Centcom), said it launched "powerful" strikes at dozens of targets in retaliation for Iranian strikes on commercial oil tankers in the Strait of Hormuz.
At 2.44am BST Centcom said it completed the round of "offensive" strikes, hitting over 80 targets "with precision munitions".
"US forces struck Iranian air defense systems, command and control networks, coastal radar sites, anti-ship missile capabilities, and more than 60 Islamic Revolutionary Guard Corps (IRGC) small boats in and near the strait to degrade Iran’s ability to continue attacking international commerce flowing through the international trade corridor," Centcom said.
Donald Trump was aware of the strikes on Iran and approved of the plans while in Ankara, Turkey, according to Axios.
Tehran condemned the US strikes as a "blatant act of aggression", adding that it would not allow US interference in the management of the waterway.
At 3.27am, Bahrain's Ministry of Interior said alarms had been activated, with citizens encouraged to go to the nearest shelter.
Kuwait's military, in a statement, said it was currently "confronting hostile missile and drone attacks".
US Central Command said it struck over 60 IRGC 'small boats'
|US CENTRAL COMMAND
It added that explosions heard were defence systems intercepting the strikes.
An hour later the IRGC said it targeted 85 US military sites "in response to US ceasefire violations".
The IRGC listed military targets in Bandar Salman, Bahrain's Fifth Naval District and Ali Al Salem Air Base in Kuwait.
It also claimed to shoot down a US MQ9 drone attempting to interfere in the operation.
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US Central Command said the 'offensive' strikes were in response to Iranian attacks on three commercial vessels
|US CENTRAL COMMAND
A US official independently said Bahrain been the target of drone strikes, according to Axios.
Videos of the strikes showed drones in the skies above Bahrain being intercepted.
The strikes follow the signing of a 14-point memorandum of understanding (MOU) last month, where Iran pledged free passage through the strait for 60-days.
Iran's top negotiator and former IRGC general Mohammad Bagher Ghalibaf listed the "major MOU violations" in a social media statement.
US strikes near the Strait of Hormuz have caused fires and black smoke to fly in the air
|REUTERS
These include violating Iranian "adjustments" in the Strait of Hormuz, persistent threats of further strikes, reinstating oil sanctions, attacks on southern Iran and attacks in Lebanon by Israel, which Ghalibaf described as "zionist".
"The era of bullying and extortion is over. It leads nowhere. We don't fold," Ghalibaf said.
Iran had earlier targeted three commercial vessels transiting the Strait of Hormuz, including the Marshall Islands-flagged Al Rekayyat, Saudi Arabia-flagged Wedyan, and and Liberian-flagged Cyprus Prosperity, Centcom said.
"Iran's demonstrated aggression was unwarranted, dangerous, and a clear violation of the ceasefire," it added.