Bab Al Mandeb, at the southern end of the Red Sea, has always been a theoretical maritime chokepoint – shown on maps but never seriously threatened, unlike the Suez Canal or Strait of Hormuz.
Now, that has changed.
Four of the world’s top five shipping companies have suspended movements through the “Gate of Tears”, as the strait is known, after Houthi forces in Yemen recently hit vessels with drone and ballistic missile strikes.
The US has stepped up its maritime presence, with American and British warships shooting down some drones. But, as I wrote in October, the proliferation of cheap and increasingly sophisticated drones poses a growing threat to energy infrastructure and transit.
The hit on the MV Palatium III, a Liberian-flagged container ship, was the first by an anti-ship ballistic missile. On Wednesday, the Marshall Islands-flagged tanker Ardmore Encounter, carrying jet fuel, also had missiles fired at it but it was not hit.
Ukraine has also pioneered the use of marine drones in its defence against Russia; something similar might make an appearance in the Red Sea.
The Houthis claim their targets are Israel-linked ships, but most of the vessels attacked have no such connections. It is not clear how directly Iran is involved in the strikes, but it does provide weapons, expertise and intelligence to the Yemeni group.
Bab Al Mandeb is only 32km wide, divided into westerly 26km and easterly 3km channels by the volcanic island of Perim, known as Mayyun in Arabic. It is even narrower than the Hormuz Strait.
About 12 per cent of the seaborne oil trade and 8 per cent of liquefied natural gas passes through Bab Al Mandeb.
Increased imports from the GCC have become increasingly critical for Europe after the near-total cessation of Russian gas and oil supplies. It is also problematic for Saudi Arabia, which has oil, petrochemical and industrial ports at Jizan, Jeddah and Yanbu on its Red Sea coast.
The Red Sea is not closed to shipping, of course, but insurance rates have risen and more ship operators may choose to avoid the area.
This is bad news for cash-strapped Egypt, which made more than $9 billion from the Suez Canal in the last fiscal year, more than 11 per cent of government revenue.