RAY SUAREZ: And we go to the Persian Gulf, where the U.S. Navy and more than 30 other countries just completed the largest exercise ever aimed at hunting and destroying mines in the waters of the Middle East.
The drill comes at an especially tense time. Israel has threatened to bomb Iran's nuclear facilities, and Iran in turn promised to mine the Strait of Hormuz, one of the world's most important shipping routes. The Navy invited 20 reporters to cover the military drill.
One of them was our own Dan Sagalyn, who produced this report.
The crew aboard the USS Ponce is a using a drone to search for hostile boats in the Persian Gulf. Video from the so-called ScanEagle is fed back to the command vessel.
Chief Petty Officer Cederick Thomas is the detachment officer in charge.
CHIEF PETTY OFFICER CEDERICK THOMAS, U.S. Navy: The imagery analysts that we have here to work the ScanEagle, they know this area. They have been doing this for at least two years looking at the Iranians, so we can tell.
RAY SUAREZ: The drone returns safely by snagging a cable with its wing.
Elsewhere, men haul out the newest tool in their arsenal, the Kingfish, an unmanned underwater vehicle that uses sonar to locate mines below the surface.
Just as this exercise was getting under way last week, General Mohammad Ali Jafari, the head of Iran's Revolutionary Guard, said:
"This is a declared policy by Iran, that if war occurs in the region and the Islamic republic is involved, it is natural that the Strait of Hormuz, as well as the energy market, will face difficulties."
Tensions between the U.S. and Iran are rising, but U.S. Navy leaders insist these exercises near Iran's coast are purely a defensive exercise.
Rear Admiral Kenneth Perry is the Navy's top anti-mine officer.
REAR ADM. KENNETH PERRY, U.S. Navy: We are conducting these exercises to demonstrate the effectiveness of coordinating the various platforms.
And the mission is to clear the -- any strategic choke point, to restore the freedom of navigation, and to restore that -- the international access to these international waters in as short a time as possible.
RAY SUAREZ: The Strait of Hormuz is potentially a choke point for the world's energy supply. One of every five barrels of oil on the planet passes through it. And it's narrow, only 25 miles across.
The two shipping lanes are even more tighter, just two miles wide in each direction. It's right off Iran's southern coast. Blocking the flow of oil with underwater mines could send oil prices skyrocketing.
Is Iran's navy able to plant those mines, how many, and what kinds of minds does Iran have?
SCOTT TRUVER, Navy consultant: Surreptitiously, they could make life miserable for us.
The Iranian threat is variously measured from roughly 2,000 or 3,000 mines to 6,000 or 7,000 mines. Most of these are relatively unsophisticated, but still quite deadly weapons.
RAY SUAREZ: Scott Truver is a Navy consultant. Besides the simple mines, he says Iran has some very modern, more complex ones, too.
SCOTT TRUVER: They have about 300 to 500 or 600, depending on who you talk to, sophisticated mines that are multiple influences. In that, I mean they can fire on a signature of a surface ship or a submarine, whether it is magnetic signature or acoustic or seismic or other signatures that a ship puts out.
RAY SUAREZ: Just about everyone the NewsHour spoke to in uniform said this exercise was not about Iran.
REAR ADM. KENNETH PERRY: It's all about mines. It's all about mine, freedom of navigation, maritime security, not about any one particular country.
MAN: The exercise area won't move.
RAY SUAREZ: But that's not how others see it.
SCOTT TRUVER: Despite the fact that the Department of Defense has indicated that it not directed at Iran, I think it is a signal to Iran.
RAY SUAREZ: How long would it take to clear mines from the strait if Iran were determined to close it?
Lieutenant Commander Scott Nietzel, commander of a mine-hunting ship participating in the exercise, wouldn't say.
LT. COM. SCOTT NIETZEL, U.S. Navy: It would depend on the number of mines, the density of mines, and what their goal in mining the strait was. There are a lot of factors that play into it. Obviously, it also depends on how many forces are committed.
RAY SUAREZ: Independent analysts offer different estimates, from a few days to many weeks, even months, to restore the full flow of commerce. This body of water is particularly hard to clear.
SCOTT TRUVER: I like to describe mine hunting on the bottom as playing the child's game "Where's Waldo?" I don't know if you have ever played that, but everybody looks like Waldo. And you have to look really close to find the real Waldo.
And that's really what it is, about sorting through the bottom to find a mine from all the other things, the fish traps, the oil cans, the trash.
RAY SUAREZ: Retired Captain Robert O'Donnell used to be the Navy's director of mine warfare and is now a consultant.
CAPT. ROBERT O'DONNELL (RET.), U.S. Navy: There's lots of ships and traffic that go through there. People throw things over the side. It sinks to the bottom. There's ridges. On the eastern side of the Strait of Hormuz, its basically a big V. that drops down really deep, so it's a challenge to go mine hunting there.
RAY SUAREZ: Along with hunting for mines, the Navy practiced protecting the vulnerable mine hunting ships, using attack aircraft flying off of aircraft carriers.
We visited the USS Enterprise in the Northern Arabian Sea. Vice Admiral John Miller commands American naval forces in the Middle East.
VICE ADM. JOHN MILLER, U.S. Navy: There are elements of the exercise that cover maritime security operations. There are elements to the exercise that cover our ability to protect our ships from aviation assets, as well as seaborne assets. And we are going to have a great opportunity to understand how all of that works.
RAY SUAREZ: But these types of so-called maritime security operations could easily morph into full-blown war, according to Alireza Nader of the RAND Corporation.
ALIREZA NADER, RAND Corporation: There's high potential for escalation between the United States and Iran. Any U.S. ships or international ships clearing those mines would be the target of Iranian anti-ship cruise missiles.
So, the U.S. would potentially have to target these missiles. But to do so, then the United States has to go after Iran's air defense.
So then you see this escalation ladder. If the U.S. has to go after the mines and then the cruise missiles and the air defense, then command and control is next. And then you basically risk a full Iranian reaction.
So, I have a hard time imagining a very limited Iranian action in the Strait of Hormuz and a limited U.S. reaction to it.
RAY SUAREZ: In a real-world situation, the U.S. wouldn't allow the Iranians to get so far as to place mines in the water and might even seek to destroy Iranian mine-laying ships in the first place, according to Scott Truver.
SCOTT TRUVER: The best mine countermeasures in the world are those that prevent the weapons from getting put into the water in the first place.
Once a mine is in the water, it's very hard to detect and determine what's there. Hey, it could look like for all intents a refrigerator.
But I don't think we'd allow anything but a handful of mines to get in the water. Once we see them doing it, and if we can make note that we do consider it an act of war, if they persisted, I think we would take them out.
RAY SUAREZ: The Navy responds by saying this international exercise is not focused on preventing mines from getting into the water, only on finding and destroying them once they are in the water.
REAR ADM. KENNETH PERRY: We need to be prepared to deal with mines going in the water. That is part of the overall defense posture, as well as dealing with a range of other threats. This exercise is focused on dealing with the mine threat and demonstrating our ability to clear mines. We have to be able to do that.
RAY SUAREZ: This U.S.-led exercise ended yesterday. Next month, Iran plans to hold a major military drill, too. It will focus on air defense in stopping attacks on its territory by aircraft.
Producer Dan Sagalyn blogs about other challenges in the hunt for mines, including jellyfish and sharks. That's on our home page. Take a look.