This tiny centre in a U.K. seaside town is the first place vessels under attack in the Persian Gulf call

In a photo released by Iranian state-affiliated news agency Tasnim, an Islamic Revolutionary Guard Corp Navy speedboat approaches a cargo ship in the Strait of Hormuz last month. (Meysam Mirzadeh/Tasnim News Agency/AP via CNN Newsource)

PORTSMOUTH, U.K. — When a vessel under attack in the Strait of Hormuz calls for help, a black phone in the corner of an office rings. It’s nothing special – just a normal office phone, a relic of the 1990s.

But when a call comes in, the three people on shift at this small office just outside Portsmouth, on Britain’s south coast, suddenly become central to the current conflict in the Middle East.

For it’s home to the U.K. Maritime Trade Operations Centre (UKMTO) – a Royal Navy-affiliated body that monitors shipping in the Red Sea, Persian Gulf and northern Indian Ocean.

And since Iran effectively closed the Strait of Hormuz more than two months ago in response to U.S.-Israeli strikes on the country, the number of emergency calls the UKMTO receives has skyrocketed.

The first moments after that call comes in “can get really stressful,” said Commander Jo Black, UKMTO’s head of operations. “The vessel may be actively under attack. You may hear alarms and sirens in the background. On occasion, we’ve even heard gunfire,” she told CNN.

Merchant vessels transiting the Strait of Hormuz have faced all manner of threats as Tehran has sought to impose its control over the crucial waterway, through which a significant proportion of the world’s oil, gas and fertilizer supply flows, in response to the U.S.-Israeli campaign. Some ships have been targeted by Iranian missile fire, others attacked by drones, yet others circled by fast attack craft.

As the war drags into its third month, the nature of the threat from Iran in the strait is changing, Black noted.

“At the start of March, we were very much seeing military action. … More recently it seems to be taking a change towards constabulary action, with vessels being challenged as they approach the Strait of Hormuz, interrogated, asked to verify their claims and, in some unfortunate cases, vessels actually being detained,” she said.

Once a ship reports such an attack, the UKMTO office scrambles into action. Its staff, known as watchkeepers, talk to the vessel’s crew and contact other nearby ships, warning them of the danger as well as asking if they can help, or provide more information. They also contact the shipping companies affected, local coastguards and military forces in the region who also might be able to assist.

It’s manned by a team of just 18 people, who cycle through 12-hour shifts, meaning that there are always three watchkeepers on at any given time, sometimes supported by an analyst too.

“If you call UKMTO, you will get a response,” Black said. “We can’t guarantee that there will be an international community available to respond directly, but we will ensure your information is shared with as wide an audience as possible to try to generate a response.”

The body has recorded 44 incidents since the Iran war began – a mixture of what it classifies as damage to ships, close quarters and near misses. Ten seafarers have died in these incidents, Black said.

Even thousands of miles away, connected to the crisis only by a phone line, it can be stressful for the watchkeepers who are “dealing with a highly emotional situation,” she added, and often establish a rapport with those on board.

Collating information

For all the frenzied response when that phone rings, a “typical day is actually relatively calm,” said Black. Banks of TV screens show different maps of the region and the shipping traffic passing through it. One map zooms in on the strait itself, a red box demarcating the “hazardous area” possibly containing Iranian mines and which vessels are avoiding.

Watchkeepers spend much of their time sifting through the 2,500 emails a day they receive from ships voluntarily sharing their positions, contact details and information about the ships around them too.

Such monitoring allows the team to often continue following a vessel even if it turns off its AIS data, an automatic tracking system. And the group’s relationship with military bodies provides another source of verification for incidents.

“We take great pains to quickly but efficiently verify information that’s received to us,” Black said. The initial reports posted on X and the UKMTO’s websites “will give a broad location of an incident, and then we will layer up on top of that with updates as we can start to verify that information through additional sources.”

Since media outlets are among those picking up these reports, the war has placed a spotlight on the normally unassuming UKMTO. Black has become used to giving interviews.

Piracy to geopolitical turmoil

The UKMTO was first established just after the September 11, 2001, terrorist attacks, as shipping companies struggled to cope with increased piracy and began liaising with the Royal Navy for ways to manage that threat. As an island nation, Britain’s interest in helping secure shipping routes matched those of the shipping companies themselves.

And the country’s colonial legacy and long seafaring history meant that, even at the beginning of the 21st century, its navy was uniquely able to take on such a role. French authorities, co-operating with their European allies and UKMTO, similarly assist and keep tabs on shipping in the Gulf of Guinea, off western Africa.

Over the past quarter-century, the UKMTO has dealt with other shipping crises too, as when Somali pirates were most active during the late 2000s or Houthi rebels in Yemen intensified their attacks on vessels passing through the Red Sea in 2023. But nothing has been like this, said Black, even though the volume of calls the office is receiving is roughly the same as when the Houthi threat was at its most acute.

“This particular situation is more challenging because there’s such a wide variety of threats that are present, and the changing geopolitical situation,” she said.

Almost every week, it seems as if instructions for ships change. U.S. President Donald Trump has repeatedly called for ships to pass through the strait and, briefly, launched an operation to assist vessels before pausing it within 48 hours at the request of Pakistani mediators. Similarly, Iran has adopted various strategies in an attempt to consolidate its control over the waterway, most recently laying out a set of new rules for vessels seeking safe passage.

All this has left around 850 major merchant ships and 20,000 seafarers stuck inside the gulf, for whom the main problem is the “uncertainty,” Black said. “What does the future hold? When are they next going to be able to get home and see their families? What does their contract and crew rotation look like?”

In such uncertain times, seafarers have come to rely on the work done by the UKMTO from thousands of miles away, perched on a ridge, from which, you can see the site of Dwight Eisenhower’s D-Day headquarters on one side and bustling Portsmouth harbour on the other.

By Issy Ronald, James Frater and John Torigoe, CNN