When Houthi militants moved onto the islands of Greater and Lesser Hanish last week, they did not simply add two specks of land to their holdings — they tightened a grip around one of the world's most consequential maritime chokepoints. The islands sit 160 kilometres north of the Bab al-Mandab strait, the narrow corridor that links the Red Sea to the open ocean and channels Saudi Arabia's oil towards its most important Asian buyers. Combined with the earlier capture of the port of Mokha and Perim island, the advance has given an Iran-backed armed group effective leverage over a corridor through which a significant share of global energy trade passes each day. The pressure on Saudi Arabia is now arriving from two directions simultaneously.

While Riyadh scrambles to recover coastline seized by the Houthis, Iran-allied militants in Iraq have struck the kingdom's east-west pipeline — the critical artery that moves crude from the Gulf through the interior to the Red Sea export hub of Yanbu. Officials have warned that repairs could take weeks. According to research firm Rystad Energy, between 2.6 million and four million barrels per day had been flowing through that pipeline since late August, a volume now described as being at risk of vanishing from global markets entirely.

The human cost of the escalation is equally stark. The International Organization for Migration reported on Monday that nearly 94,000 people have been displaced inside Yemen since fighting intensified this month, with roughly 200 schools repurposed as emergency shelters in the country's south-west. More than 2,000 people have crossed the sea to reach Djibouti — bringing the conflict to within 32 kilometres of a United States military installation on the Horn of Africa, a proximity that has quietly unnerved defence planners on both sides of the Atlantic. For oil traders, the arithmetic is becoming increasingly uncomfortable.