Iran said Sunday it struck an unmanned U.S. vessel trying to enter the Strait of Hormuz, a claim the U.S. military dismissed as a total lie.

The purported attack came a day after the U.S. military said forces struck three Iranian oil tankers in response to Navy warships being targeted with ballistic missiles. The Islamic Revolutionary Guard Corps claimed its navy attacked a remotely operated U.S. military vessel that was attempting to enter a protected area of the strait.

U.S. Central Command spokesman Capt. Tim Hawkins called the Iranian report a total lie. No confirmation of damage or any U.S. casualties has emerged from American sources.

The exchange marks the latest escalation in renewed hostilities that resumed last week after roughly a month of relative calm. The broader conflict began with U.S. and Israeli attacks on Iran on February 28. A fragile ceasefire was announced in June, but on-and-off fighting has persisted as negotiations collapsed.

On Saturday, the IRGC said it launched ballistic missiles at a U.S. aircraft carrier and a guided-missile destroyer, accusing the vessels of harassing Iranian ships and participating in a maritime blockade. U.S. forces reported no personnel harmed and retaliated by striking three Iranian oil tankers linked to a shadow network funding the IRGC and its proxies.

CENTCOM said the strikes targeted the M/T Kylo, M/T Stark I, and M/T Downy, with one vessel sinking after its crew was directed to abandon ship. Admiral Brad Cooper stated that attacks on American ships would bring an even higher economic cost to Iran.

Iran condemned the tanker strikes as illegal and aggressive, vowing a faster and more intense response to further U.S. actions. The IRGC warned commercial vessels against using unauthorized routes through the Strait of Hormuz.

Experts have described the back-and-forth as a dangerous escalation that threatens commercial shipping and global oil supplies through the critical waterway.