Bab el-Mandeb has become the second front in a war being fought largely at sea. Houthi militants have finished preparing to attack shipping at the Red Sea’s southern gateway, according to a warning issued to mariners by a US Navy-led maritime security group.

The implications reach well beyond Yemen. With Iran already attacking tankers in the Strait of Hormuz, the world’s two most important oil chokepoints are now simultaneously threatened.

The Warning

The Joint Maritime Information Center, headquartered in Bahrain, issued the notice Tuesday.

“Sources close to the group stated that the Houthis have completed preparations to attack shipping, including the deployment of missiles and drones positioned near Bab el-Mandeb,” the center told commercial vessels.

The European Union’s naval mission followed on Wednesday with more specific guidance, advising that merchant vessels connected to Israeli, US or Saudi interests should avoid transiting the Red Sea and Gulf of Aden until the threat level falls.

The Embargo Against Saudi Arabia

The Houthis declared a maritime embargo against Saudi Arabia on Monday, threatening to sever the kingdom’s oil exports through the Red Sea and Bab el-Mandeb.

Their stated terms are sweeping. According to the EU naval mission’s notice, the group has said all vessels loading or discharging cargo at or from any Saudi ports are prohibited.

That is not a targeted restriction. It applies to any ship touching a Saudi port, regardless of flag or ownership.

Why Saudi Exports Matter So Much Right Now

Here is the detail that makes this dangerous for the global economy rather than merely for the region.

Riyadh has been diverting millions of barrels per day through a pipeline to the Yanbu terminal on the Red Sea, deliberately bypassing the Strait of Hormuz where Iran is attacking shipping.

The numbers show how heavily Saudi Arabia has leaned on that route:

• Exports through Bab el-Mandeb from Yanbu reached 3.5 million barrels per day in June
• The same period last year saw just 240,000 barrels per day

That’s a more than fourteenfold increase, according to Kpler data.

Yanbu has functioned as the relief valve for global oil markets during the Hormuz crisis. The Houthi embargo is aimed precisely at closing it.

Traffic Is Already Reacting

The JMIC noted Tuesday that commercial traffic continued moving through the southern Red Sea and Bab el-Mandeb with no attacks in the previous two days, and assessed the threat level as moderate.

“No changes to commercial routing or transit patterns occurred, and vessels continued to use established lanes without disruption,” the centre said.

Shipping data tells a different story.

Kpler observed a 34% drop in traffic through Bab el-Mandeb on Tuesday compared with Monday, the day the embargo was declared.

Maritime intelligence firm Windward reported that four tankers carrying Saudi cargo turned around before reaching the strait on Tuesday. Between them they were carrying 3.8 million barrels of crude oil, gasoil and naphtha.

Shipowners are not waiting for the threat assessment to be upgraded. They are rerouting on the announcement alone.

Hormuz Keeps Getting Worse

The other chokepoint has moved past threats into sustained attack.

Iran has escalated its strikes on tankers in the Strait of Hormuz, attempting to force vessels to transit through Iranian territorial waters rather than international lanes. Three tankers carrying crude, refined products and chemicals were attacked off the coasts of Oman and the United Arab Emirates this week alone.

The cumulative toll since July 6, according to the International Maritime Organization, a United Nations agency:

• A dozen ships attacked in and around Hormuz
• Two seafarers killed
• More than a dozen injured

Those casualties are worth pausing on. Commercial crews are civilians doing ordinary jobs, and they are now the ones absorbing the human cost of this conflict at sea.

A Coordinated Squeeze

The strategic logic connecting these two fronts is not subtle.

Iran cannot export its own oil under the American naval blockade. Its response has been to make the Strait of Hormuz unusable for everyone else. Saudi Arabia’s answer was to route more crude around Hormuz entirely, through the Red Sea.

The Houthi embargo closes that workaround.

Taken together, the effect is to leave Gulf producers with no clean path to market. Whether that pressure is intended to force negotiations or simply to maximise damage, the practical consequence is the same for anyone buying oil.

What to Watch

Three indicators will show whether this escalates further.

The first is whether the Houthis actually fire. Preparations and declarations have already moved markets. Confirmed attacks on vessels would move them considerably more, and would likely trigger a broader withdrawal of commercial shipping from the corridor.

The second is insurance. War risk premiums for these routes tend to rise faster than the physical threat, and at a certain point coverage becomes prohibitive regardless of whether ships are actually being hit.

The third is Saudi Arabia’s response. Riyadh and the Houthis exchanged fire last week for the first time in years, straining a truce that has held since 2022. An embargo on Saudi exports puts significant pressure on that arrangement.

For now, Bab el-Mandeb remains open and traffic continues, if lighter than before. The missiles are in position, the warnings have been issued, and a third of the ships that would normally be there have already decided not to find out.