On Monday, the Iran-aligned Houthi movement in Yemen announced a naval blockade against Saudi Arabia, warning that vessels loading or discharging cargo at Saudi ports could become military targets. The following day, two oil tankers carrying Saudi crude to China and India reversed course in the Red Sea, heading north towards the Suez Canal instead of transiting the Bab el-Mandeb strait, according to shipping data cited by Reuters. A third tanker due to load at the Saudi port of Yanbu also turned back near Oman.

US President Donald Trump told reporters on Tuesday that the blockade had not yet occurred but that "if something like that happens, we take care of it", adding that the US had previously acted against the Houthis. Saudi Arabia condemned the Houthi announcement, with its foreign ministry expressing "the most energetic condemnation" and stating that the kingdom would take all necessary measures to protect its vessels. The Houthis justified the blockade as a response to what they described as a Saudi blockade of Yemen and an attack on Sanaa airport, which they attributed to Riyadh.

The Bab el-Mandeb strait, which the Houthis control the Yemeni coastline overlooking, is a critical chokepoint for Saudi oil exports. Since the Strait of Hormuz became effectively closed due to the US-Iran conflict, Saudi Arabia has relied on its Red Sea port of Yanbu as an alternative export route, shipping over 3.6 million barrels per day through the Red Sea, according to maritime data firm Kpler. The diversion of tankers via the Suez Canal and then around the Cape of Good Hope could add weeks to several months to delivery times, according to conflicting shipping estimates, raising fuel and insurance costs.

The Houthi move follows a dispute over an Iranian plane carrying a Houthi delegation that was prevented from landing at Sanaa airport earlier in July, which the group blamed on Saudi Arabia. Analysts cited by AFP and other outlets noted that Iran had been pressing the Houthis to close Bab el-Mandeb if the US continued attacks on Iranian infrastructure, potentially creating simultaneous crises at both Hormuz and Bab el-Mandeb. The 2022 truce between the Houthis and Saudi Arabia, already fragile, has been further undermined by recent exchanges of fire. No attacks on commercial vessels under the new measures had been reported as of Tuesday, but war risk insurance costs have risen.