Naveen Das, a senior oil analyst from Kpler, told BBC Verify the only option left to the Saudis if the Bab al-Mandab Strait is effectively closed would be to move oil all the way through the Mediterranean and around the southern tip of Africa to get to Asia.

The impact of the blockade on consumers won't be immediate, but the conflict with Iran has made the global energy system more vulnerable to shocks like these, Das added. "We could weather it for two weeks, three weeks, even a month, but even in that time, we will see higher freight rates, higher energy prices and that bleeds into higher energy consumer costs."

Ships close to the Red Sea are also broadcasting messages in an attempt to deter attacks, a common practise in the region since the Houthis targeted vessels during the war in Gaza.

At least 50 vessels in the region are broadcasting they have armed guards on board, according to data from MarineTraffic.

Martin Kelly, from crisis management firm EOS Risk Group, told BBC Verify that captains will fear the "Houthis might read your situation wrong" and think their ships have "called at a Saudi port in the past, then therefore you could be attacked".

"A lot of these ships are very large crude oil carriers. I think the damage would be catastrophic. There would be certainly be deaths onboard these ships," he added.

Additional reporting by Barbara Metzler