The UAE accused Iran of a "brazen" attack on two tankers in the Strait of Hormuz, killing one and wounding eight, as Donald Trump said the US would impose a 20% charge as part of a new blockade on the waterway.
The US president said they were hitting Iran "very hard" as strikes were launched for the third consecutive night amid escalating attacks between the two countries.
Iran's foreign minister responded to the announcement of a blockade by saying that Tehran would remain the Strait's "GUARDIAN," using Trump's word.
The dispute over control of the Strait of Hormuz threatens to derail efforts to end their war, but Trump insisted a deal was still possible.
As tensions over the international waterway ramped up, the United Arab Emirates said on Monday night that Iranian cruise missiles targeted two national tankers, killing an Indian crew member and wounding eight others, four of which were serious.
Six of those injured were Indian, while two were Ukrainian, the UAE Ministry of Defence said in a statement on X.
"The Ministry of Defense condemns this brazen attack, which constitutes a serious violation and a clear breach of international law, threatening the security and stability of the region," it said.
Iran's Islamic Revolutionary Guard Corps (IRGC) later confirmed the strikes via a statement to Telegram, where it said two tankers had ignored warnings, turned off navigation systems and attempted to pass through a mined route.
In response, the IRGC said it had hit the tankers and disabled them.
It added that "co-operation with the aggressor enemy" would only lead to regret, damage and delays in opening the Strait - as well as the "creation of an energy crisis in the world."
Oil prices edged higher in Asian trade on Tuesday. Brent crude was up by 0.7% at $83.87 (£62.79) a barrel, while US-traded oil was 0.9% higher at $79.04.
That followed a more than 9% jump in the price of Brent on Monday as the conflict escalated.
