Credit: U.S. Navy via Getty Images

(CNN)-- US Central Command (CENTCOM) announced that it used, for the first time, one-way attack (suicide) drones and one-way attack unmanned surface vessels in the strikes it launched against Iran on Sunday.

The command did not specify in its statement the exact type of these drones or the number of each category that participated in the attacks.

US attack drones had seen their first use early in the war with Iran, when CENTCOM deployed the 'Low-Cost Unmanned Aerial Combat System' (LUCAS), essentially a replica of Iran's Shahed-136 drones, which Russia has used in large numbers in its war on Ukraine.

CENTCOM said in a social media post at the time: 'These low-cost drones, inspired by Iran's Shahed drones, are now executing American retaliatory strikes.'

As for the unmanned surface vessels, Karl Schuster, former director of the Joint Intelligence Center of US Pacific Command, said the US had been conducting experiments on several types.

Schuster told CNN that 'the most suitable for one-way attacks is the Fleet-class USV (unmanned surface vessel).'

He added that these vessels were originally designed for mine countermeasure or anti-submarine warfare missions, but their speed exceeding 40 miles per hour makes it possible to adapt them for one-way attacks, also known as 'suicide attacks.'

Schuster noted that the cost of a single vessel exceeds $2 million, but he affirmed that they 'will be difficult to stop,' adding that the USV unmanned vessels and LUCAS aerial drones are designed to be launched from US Navy littoral combat ships.