The United States is training Gulf allies to "protect navigation" in the region's troubled waterways, as it seeks to build an alliance to contain Iran.
Washington's three-week International Maritime Exercise (IMX), which started on October 21, came after a number of commercial vessels were attacked in the Gulf from May, ratcheting up regional tensions.
Washington and other Western powers blamed the incidents on Iran, which has denied any involvement.
On Tuesday, the US invited international media to see part of the IMX, the second-largest maritime exercise of its kind.
The manoeuvres involve 5,000 personnel, 40 vessels and 17 aircrafts from 50 countries deployed to the strategic waterway that separates Iran from the pro-US Arab Gulf monarchies.
"This is the first time we are taking part in the IMX," the head of a Saudi naval de-mining team, Ali Bin Shreidi, told AFP aboard the Cardigan Bay, a British Royal Fleet Auxillary landing ship 40 miles (65 kilometres) off Bahrain's coast.
- 'Fighting mines' -
The officer and his three-member team were taking part in order "to increase our capabilities and share our expertise in fighting mines, in order to protect navigation," he said.
In June, the US Navy alleged that a mine resembling Iranian weaponry was used in an attack on the Japanese-owned Kokuka Courageous tanker, targeted as it passed through the Gulf of Oman.
Then in July, Iranian Revolutionary Guards seized a British-flagged oil tanker, holding it for more than two months before releasing it.
"One of the biggest reasons for us being out here is to build international relations," said US Navy lieutenant Jonathan Phares who was among 300 personnel from the US, France and the Gulf on the Cardigan Bay.
Those aboard showed off diving gear, underwater imaging kit and speed boats during a tour of the gun-metal grey vessel, while others demonstrated mine detection equipment.
- 'We've been used more' -
But they were tight-lipped about tensions with Iran.
"We've been used more than in the past," said a US mines expert who declined to be named.
In response to the string of incidents in the region's vital shipping routes, the US formed a naval coalition to protect navigation in a waterway that is critical to global oil supplies.
Bahrain, which hosts the US Navy's Fifth Fleet, joined the US-led naval coalition in August. Saudi Arabia and the United Arab Emirates followed suit in September.
The United Kingdom and Australia are the main Western countries to have agreed to send warships to escort commercial shipping in the Gulf.
Animosity between Tehran and Washington and its allies has soared since the US unilaterally abandoned a multinational deal on curbing Iran's nuclear programme last year and reimposed heavy sanctions on the Islamic republic.
On September 14, drone strikes targeted two Saudi oil facilities, causing catastrophic damage and temporarily knocking out half of the kingdom's oil production.
The attacks were claimed by Yemen's Huthi rebels who are battling a Saudi-led coalition, but Washington and Riyadh blamed Iran, saying the strikes were carried out with advanced missiles and drones.
Most European states have declined to participate in the naval coalition, fearful of undermining their efforts to save the nuclear accord with Iran, which was badly weakened by the US withdrawal.