London —

A narrow waterway located at the mouth of the Red Sea between Yemen and Djibouti has provided an escape hatch for a sizeable chunk of the Middle East’s oil. That lifeline is now looking increasingly shaky.

For weeks, Yemen’s Iran-backed Houthi rebels have threatened shipping in the Bab al-Mandeb strait, attempting to open a new front in the war between Tehran and Washington, now in its seventh month.

In the past 48 hours, the Houthis have dramatically tightened their grip on the shipping route, capturing both the port city of Mocha and - according to Yemeni government sources - the strategic Perim Island in the middle of the maritime chokepoint.

The strait has long been a vital artery of global trade, but has become significantly more important since the US-Iran war effectively shuttered the nearby Strait of Hormuz.