The US military said Tuesday that one of its underwater drones “malfunctioned” after Iran said its forces captured an American unmanned submarine in the strategic Strait of Hormuz.

“An underwater drone operated by US forces malfunctioned more than a day ago. It was surveying regional waters in support of ongoing operations,” US Central Command Spokesman Capt. Tim Hawkins said, without mentioning whether the device was seized by Iran.

“The defective drone was an older model that neither collected sensitive data nor carried any classified sonar or radar equipment,” Hawkins added.

Iran’s IRGC had earlier said they seized a US drone at the “entrance to the Strait of Hormuz in a complex intelligence and operational action,” describing it as “one of the most modern, unmanned, and smart submarines” operated by US forces.

Iran has maintained a blockade of the Strait of Hormuz, which normally carries about a fifth of the world’s oil and liquefied natural gas exports, since the outbreak of the war in late February, while the US has imposed its own blockade of Iranian ports.