The Iranian Revolutionary Guard said it had attacked an unmanned US military surface vehicle, which it said was trying to enter a protected area of the Strait of Hormuz.
The attack came after US strikes on three Iranian oil tankers in the Persian Gulf. The Revolutionary Guard said the tankers were sailing in passages that Tehran considers unauthorized.
According to the Iranian statement, in addition to the oil tankers, three US ships were also targeted in other areas. Tehran has warned other ships not to attempt to pass through sea lanes that are not approved by it.
Meanwhile, the US Central Command (CENTCOM) confirmed that it had struck three Iranian tankers. The US military said that two of them were "permanently disabled" while the third was "completely destroyed".
According to CENTCOM, the tankers were part of a covert network that, according to the US, finances the Iranian Revolutionary Guard and its affiliated groups with billions of dollars.
One of the ships was hit near Kharg Island, home to Iran's main oil export terminal in the Persian Gulf. Another was targeted near Yask, near the Strait of Hormuz, and the third in the Gulf of Oman.
Iran has described the US attack on the tankers as an "act of desperation", at a time when Tehran continues to restrict the movement of ships through the Strait of Hormuz, one of the most important sea routes for global energy trade.
The latest clash comes as diplomatic efforts to end the war in the Middle East have stalled, while the US has reiterated its intention to increase economic pressure on Iran.
The tensions have also been accompanied by new military threats. The commander of Iran's Joint Chiefs of Staff, Khattam al-Anbiya, warned that if hostilities continue, attacks on US warships in the region will be even more severe.
Washington said it launched the latest strikes after a US aircraft carrier and a destroyer came under multiple Iranian attacks. The US military said no US personnel were injured in the incidents.
