With just hundreds of meters setting them apart, US ships guarding Iraqi oil terminals and Iranian Revolutionary Guard boats stare at each other across the waters of the northern Gulf.
The maritime zone lying at the edge of Kuwait's, Iraq's and Iran's territorial waters makes for "a fairly heady cocktail," said Captain Adrian Bell, commander of HMS Campbeltown, a British frigate which is part of the coalition naval group patrolling the area.
Hence, caution is the order of the day for the seven or eight, mostly American, ships making up the naval force and currently led by the cruiser USS Chosin.
The hundreds of boats which regularly come close to three-kilometer (1.8-mile) exclusion zones enforced by the coalition around the Iraqi oil terminals of Khor Al-Amaya (KAAOT) and Basra (ABOT) do not always carry Iraqi fishermen.
They also include Iranian dhows and ships of the Revolutionary Guards.
Each week, an average of two to three Iranian boats cross into Iraqi territorial waters, said Lieutenant Jennifer Graham, one of 35 women among the crew of the Australian frigate HMAS Newcastle.
"It's not just fishing boats. It's also Revolutionary Guard boats," she said.
But unlike the usual practice in such cases, "we don't board them. We talk to them and they leave," Graham said.
The presence of these Iranian boats is not surprising, considering that the eastern limit of the exclusion zones enforced around the oil terminals is just 200 to 300 meters (yards) from Iranian territorial waters.
To reduce the risk of friction, the commander of the naval group patrolling the area, US Navy Captain Hank Miranda, has imposed in some areas an additional "buffer zone" of several hundred meters along Iran's territorial waters.
The "buffer zone" is off limits to coalition ships.
But Miranda is adamant that the hostility and frequent rows between Tehran and Washington, which don't have diplomatic relations, have no effect on his mission.
"Personally, I don't think Iran is a problem," he said, calling the Iranian ships "non-combative."
"They come when we ask for help," he said during an interview aboard the USS Chosin, recounting how Iranians took part in a search-and-rescue mission when a US sailor fell into the waters of the Gulf a few weeks ago. The body was never recovered.
"It's a very professional relationship," Miranda insisted.
But despite the apparent serenity, the British commander, Bell, said some of the US crews appear to be jittery about the Iranians' proximity.
"Sometimes, a couple of boats from the Revolutionary Guard pop over. They pop over out of cheekiness," said Bell on the deck of the Campbeltown.
"It does surprise me the amount of interest a bunch of guys with AK-47s can generate among US crews," he said, visibly amused.
US patrol boats are always quick to respond, Bell added.
"You have the patrol boats. They start to go near them. We have to remind them, 'Er, guys, that's not what you are here for,'" he said.
It's almost as if the Iranians were "tweaking the tiger's tail... just to see what happens when they pop over," Bell added.
In the longer term, "the moment the coalition forces withdraw... some form of vacuum is created. Somebody is going to want to fill that vacuum," he warned in an apparent reference to Iran.
"Unless you have some agreement in place, it could be a rough place," he said.
But Miranda has a simple answer.
"The US Navy has maintained a presence in the area since 1947... I don't think that we'll ever leave," he said.