How the Strait of Hormuz is monitored as US and Iran escalate attacks

The Strait of Hormuz is once again the scene of fighting, with Iran and the United States States vying for control of the strategic waterway and continuing to trade fire in the early hours of Thursday. 

When the US and Israel launched the war on Iran on 28 February, Tehran effectively closed the strait to shipping traffic.

That move sent the price of oil, fertilizer and many other goods soaring far beyond the region and gave Iran major leverage in negotiations.

So how do the countries directly involved in the conflict — and the international community —know what's happening in this vast stretch of water?

"There's no one monitoring authority," explains Commodore Steve Prest, a retired naval officer and Associate Fellow at Royal United Services Institute (RUSI).

Both sides, he says, will be "monitoring it through a number of different means, fusing together lots of different information and data sources to create a coherent picture of activity in and around the Strait of Hormuz"

Prest says that picture is built using radar from warships, surveillance drones, maritime patrol aircraft, satellites and shipping data.

"There are commercial solutions out there which will allow you to look at, for example, electronic emissions that come from ships," Prest says.

"So ships are transmitting on radios, or they're transmitting them on maritime radars, or even perhaps just an infrared view, so you get the heat plume coming out of the ship's funnel. Those things are observable from space."

Back-and-forth strikes

The US intensified its strikes on Iran early Thursday, hitting targets farther north and firing into a ship the US accused of trying to break its naval blockade on the Islamic Republic.

Iran retaliated by launching missiles and drones at US allies in the region, and warned its attacks may escalate.

Days of back-and-forth strikes by the US and Iran across the Middle East have shredded the interim deal to end the Iran war.

Already, Iranian officials say US strikes have killed more than 35 people and wounded over 300 others.

Both sides have blamed each other for the breakdown of talks.

"We had a deal yesterday, or the day before yesterday, it was all done," US President Donald Trump said on Monday. "And then they broke up that deal immediately because they found out there was something in the deal they didn't like."

Iran's deputy foreign minister Kazem Gharibabadi denied a day later that his country had ever left the negotiating table.

According to Prest, monitoring will be essential in securing any form of peace.

"There is not a lot of trust at the moment between the United States of America and the Iranian regime," he says. "And so whatever happens will need to be monitored and over time to be able to build a position of trust."

The US has threatened to reopen the strait by force, but experts say that would require a much bigger armada, if not tens of thousands of ground troops.