The Houthi maritime blockade of Saudi Arabia, declared on 20 July 2026, produced a sharp and then remarkably flat effect on traffic through the Bab al-Mandeb. Transits fell from 354 in the week of 13 to 19 July to 269 in the week beginning 20 July, a drop of roughly 24 percent. Preliminary figures for the following week showed 266. The decline arrived immediately and then held its level instead of continuing.
That shape matters more than the headline percentage. A general panic in a chokepoint looks different: transits fall for several consecutive weeks as charterers work through existing fixtures and then refuse new ones, and the curve keeps sliding until a floor of unavoidable regional trade is reached. What happened in the Red Sea in late July was a single-step adjustment by one class of operator, followed by stability.
The disruption is concentrated in tankers
Mainstream tanker traffic, meaning tankers outside the sanctioned-oil shadow fleet, fell about 42 percent in the week after the blockade announcement, to 53 transits. Container and general cargo movements were far less affected, and Suez Canal throughput stayed broadly level. An uptick in VLCC movements suggests owners rerouting and reorganising rather than abandoning the corridor.
This is consistent with a targeting policy that discriminates. The Houthis have claimed attacks on Saudi-linked vessels, energy infrastructure at Jizan and Yanbu, and an airport, all framed as enforcement of a blockade against the kingdom specifically. A boxship operator with no Saudi cargo and no Saudi ownership in the chain reads that framing and keeps sailing. A tanker charterer lifting Saudi crude at a Red Sea terminal reads it and reprices, or declines.
Calibration is a capability, not a courtesy
The 2023 and 2024 campaign against shipping was broad, and it emptied the corridor; traffic bottomed near 20 to 23 vessels a day. The current campaign has produced a fraction of that damage to general trade while imposing concentrated cost on one state. The group has learned that a narrow target set buys it political room, keeps European and Asian shipowners from demanding a naval response on their own behalf, and preserves the Bab al-Mandeb as a functioning waterway it can threaten again later.
The corollary is that the flat traffic line is not evidence of resilience in the market. It is evidence of a choice by the attacker, and choices reverse. The variables that would move traffic sharply lower are a strike on a vessel with no Saudi connection, a mining incident, or a declared fee regime that makes every transit a transaction with Sanaa. Any of those would push war risk premiums past the point where the Cape routing becomes the default again for Asia to Europe cargo.
What to watch in the data
Weekly transit counts alone will understate the pressure. The more sensitive indicators are the ratio of mainstream to shadow-fleet tanker transits, the share of Saudi crude loading at Yanbu versus lightering offshore, and whether war risk quotes for Saudi-linked hulls decouple further from the general Red Sea rate. A widening spread between those two premiums is the clearest market signal that the discrimination is holding. A narrowing spread means underwriters expect the target set to broaden.