More than three dozen nations have converged on the seas around Bahrain for a massive military minesweeping exercise.
The at-sea maneuvers will involve a series of techniques and involve surface ships, aircraft, and underwater "explosive ordnance disposal" diving teams during the nearly two weeks of International Mine Countermeasure Exercise.
Remote piloted submersibles, known as unmanned underwater vehicles, or UUVs, will get their most sustained test yet in combination with regular forces.
The U.S. military says these exercises are strictly "defensive," but the show of force in light of Iran's threats to mine the Strait of Hormuz is hard to ignore.
In a typical week, officials say more than 500 ships will sail through the Strait, carrying everything from oil to natural gas.
The United States has been promoting the fact that more than 30 nations are participating in the exercises.
But CNN has learned that so far, two thirds of those nations do not want to have their participation made public. And only half a dozen or so will send actual ships to the exercise.
The situation suggests that in any real minesweeping scenario, or conflict with Iran, the U.S. military would bear the brunt of the fight.
The United States has a lot of naval power in the region. But the American military is careful not to unnecessarily provoke Iran, especially with tensions so high after toughened economic sanctions and much talk in the U.S. and Israel about whether Iran's progress in developing nuclear capabilities will warrant military action to stop it.
"Any action can instantly trigger a disproportionate reaction, and we have to be aware of that," Vice Adm. Ted Carter told CNN. The U.S. military is trying to strike a balance between protecting the free transit of the waterway, while avoiding an inadvertent conflict with Iran.
In an indication of how sensitive the waterway has become, some U.S. Navy ships passing through the Strait of Hormuz are equipping their guns with cameras.
The gargantuan aircraft carrier USS Enterprise, on its last cruise, has made eight trips through the Strait on its current deployment. Crew members showed CNN where they strap small cameras to each gun when nearing certain ports or passing by certain areas in the Strait.
Vice Adm. Ted Carter told CNN, "If anything were to happen, we want to have video evidence of it as much as we can. So that when we say 'This is what happened,' the video shows we mean what we say, and that we're telling the truth about what went on."