The US Navy has deployed small underwater drones capable of destroying sea mines to the Persian Gulf, The Los Angeles Times reported on Thursday.
According to the report, deployment of the German-made device known as SeaFox is part of an American military build up aimed at stopping Iran from closing the strategic Strait of Hormuz.
The first drones began arriving in recent weeks as the latest round of negotiations with Iran over its nuclear development program appeared to have stalled.
On Saturday, a US navy ship that had been slated for decommissioning was sent instead to the Gulf to help mine-clearing operations, the US Fifth Fleet based in Bahrain said, in the latest move in a gradual US build-up as tensions with Iran smoulder.
Four US minesweepers arrived in the Gulf last month to bolster the Fifth Fleet and ensure the safety of shipping routes in a waterway through which 40 percent of the world's seaborne oil exports flow.
Tensions have simmered in the Gulf with big-power diplomacy to ease the nuclear dispute at an impasse and Israel renewing veiled threats to attack Iranian atomic sites from the air if sanctions and negotiations fail to curb Iran's nuclear advances.
A string of hawkish Iranian statements - including a renewed threat to close the Strait and destroy US bases in the region "within minutes" of an attack - over the past week helped thrust benchmark Brent crude oil prices above $100 for the first time since June.
Iran has repeatedly warned of reprisals for any Israeli or US-led strike on its nuclear installations, whose activities it says are purely peaceful but the West suspects are geared to developing the means to produce nuclear arms.
Reuters contributed to this report.