Toplines

The Houthi offensive to capture territory along Yemen’s southern Red Sea coastline advances common Houthi and Iranian objectives by improving Houthi positions to threaten shipping through the Bab al Mandeb Strait.[1] The Houthis captured Mokha Port in Taiz Governorate from Republic of Yemen Government (ROYG)-affiliated forces on September 10.[2] The Houthi seizure of Mokha and additional territory along southwestern Yemen’s coastal plain resulted from conditions created by nearly a week of fighting between Houthi and ROYG forces along frontlines in Hudaydah and Taiz governorates, as described in greater detail below. The Houthis’ improved position along the Red Sea coastline supports current Iranian objectives by providing Iran with additional leverage in its broader regional campaign against the United States. Houthi gains along the Red Sea coast nevertheless do not necessarily indicate that the Houthis will fully align their future operations around the Bab al Mandeb with Iranian objectives.

The Houthi offensive to capture territory near the Bab al Mandeb advances Iranian objectives under the current regional campaign that Iran is waging against the United States and its allies. Iran is currently pursuing a regional campaign that aims to degrade the United States and its allies’ willingness to sustain the war against Iran and coerce the United States to surrender to Iranian demands. Recent Iranian attacks on US regional assets and civilian shipping indicate that Iranian decision-makers — currently dominated by the hardline faction led by Islamic Revolutionary Guards Corps (IRGC) Commander Major General Ahmad Vahidi—are not satisfied with the current status of the war because Iran has not yet achieved its key objectives in the conflict, such as securing recognized control over the Strait of Hormuz.[3] These decision-makers appear intent on trying to change the current trajectory of the conflict through the use of military force.[4] Iran has recently pursued the following lines of effort under this regional campaign:

• Targeting US naval forces. Iran has aggressively targeted US naval forces in recent days, likely to degrade the United States’ willingness and ability to continue enforcing the US naval blockade on Iranian ports.[5]
• Attacking US forces across the region. Iran has attacked US bases in Jordan, Kuwait, and Bahrain in recent days in order to weaken the resolve of the United States and its regional allies that host US troops.[6] Iran recently fired a cluster warhead—which contains submunitions that disperse over a wide area — in an attack on a US base in Jordan on September 9, which suggests that Iran sought to inflict greater damage or casualties.[7]
• Disrupting traffic through the Strait of Hormuz. Iran has continued to strike commercial vessels in the Strait of Hormuz to disrupt international shipping and raise oil prices.[8] Iran more recently appears to be targeting stationary commercial vessels in the Persian Gulf and Gulf of Oman, likely to deter the United States from conducting further strikes on Iranian oil tankers.[9] Iran has also recently attempted to lay more mines in the strait.[10]

Iran is now attempting to improve its own position along the Bab al Mandeb through its partnership with the Houthis in order to expand its ability to disrupt international shipping routes beyond the Strait of Hormuz as another line of effort with its current regional campaign.[11] A significant percentage of global trade passes through the Bab al Mandeb daily, and Iranian efforts to exert control over the Strait of Hormuz have increased international reliance on the Bab al Mandeb and Red Sea for the movement of Gulf energy products.[12] Disrupting traffic in the Red Sea through Houthi control over the Bab al Mandeb would enable Iran to attempt to drive further concessions from the United States and regional Gulf allies by disrupting energy and shipping flows and imposing economic costs on Gulf countries. The Houthis do not necessarily need to halt shipping through the Bab al Mandeb for Iran to exploit recent Houthi gains. The Iranian regime has repeatedly used the threat of Houthi attacks in the Bab al Mandeb to attempt to deter the United States from striking critical infrastructure in Iran.[13]

The Iranian regime has actively provided military and financial support to aid the Houthi offensive to seize Mokha Port.[14] Yemeni government, Iranian, and regional sources separately told Reuters on September 10 that Iran provided arms and guidance to the Houthis to support the offensive to seize Mokha Port, expand Houthi control over the vital Bab al Mandeb Strait, and open a new front in Iran’s conflict with the United States.[15] US officials told CNN on September 10 that they believe that there are currently hundreds of IRGC officers in Yemen who are working alongside the Houthis with the goal of ultimately shutting down the Bab al Mandeb Strait.[16] ROYG sources identified IRGC Quds Force Commander Abdolreza Shahlaei as the leader directing the Houthi campaign along the Red Sea coast.[17] Shahlaei is a figure who has been heavily involved in providing military and financial support to the Houthis, including in the 2023-2025 Houthi campaign against Red Sea shipping.[18] Anti-Houthi media reported on August 3 that Shahlaeli met with Houthi Supreme Leader Abdulmalik al Houthi in Saada Governorate in northern Yemen to discuss unspecified operations.[19] Shahlaeli was also reportedly supervising Houthi operations to dismantle anti-Houthi tribal mobilizations along the Houthi frontlines in eastern Yemen in late July, which underscores the direct role that the Iranian regime plays in supporting Houthi operations.[20]

The Houthis and Iran may currently share a common objective in Houthi control over the Red Sea coastline, but the nature of their relationship means that the Houthis will independently determine their level of involvement in supporting other Iranian objectives. The Houthis view themselves as a coequal partner to Iran rather than as an Iranian proxy. Iran and the Houthis share strategic alignment over key objectives, but the Houthis have historically pursued objectives for their own benefit as well as Iran’s. The Houthis have their own strategic objective to ultimately establish control over all of Yemen under a strict Shia-Zaydi theocracy ruled by their own Supreme Leader Abdulmalik al Houthi.[21] Both Iran and the Houthis aim to decrease US influence in the region to impose their own vision of a regional order. Iran has long viewed the Houthis as a partner that can help implement Iran’s vision, even though the Houthis sometimes have divergent aims.

Iran may seek to close the Bab al Mandeb in order to drive concessions from the United States, but the Houthis may separately calculate that such an action would not support Houthi interests. ISW-CTP assessed in early April 2026 that the Houthis did not join Iran’s regional economic warfare campaign in order to avoid retaliation from the United States and its allies that might jeopardize the Houthi’s domestic position.[22] The Houthis refrained from following through on threats to disrupt shipping in the Bab al Mandeb until Houthi leaders decided to impose a blockade on Saudi vessels and ports in late July 2026 in an effort to secure key Houthi demands from Saudi Arabia.[23] It is unclear at this time if the Houthis are seizing territory near the Bab al Mandeb as part of a larger effort to halt all commercial shipping through the strait, particularly given that doing so might prompt significant retaliation from the United States, Saudi Arabia, or other US allies.

The Houthis’ capture of Mokha Port and reported landings on islands near the Bab al Mandeb may set conditions for potential Houthi efforts to establish themselves as a legitimate authority and guarantor of passage through the strait, as Iran has attempted to do in the Strait of Hormuz.[24] Iran is attempting to establish a clear precedent in which an actor can assume control over an international waterway by attacking ships that pass through certain chokepoints.[25] This precedent contradicts international law and maritime norms about freedom of navigation through international waterways.[26] The Houthis have referenced this Iranian model for assuming control over international chokepoints and argued that such a model may apply to the Houthis in the Red Sea, including through the possible imposition of tolls.[27]

The Houthis’ consolidation of control over Mokha Port, which is approximately 70 kilometers from shipping lanes through the Bab al Mandeb, would significantly improve Houthi capabilities to target vessels travelling through the strait. Closer positions to Bab al Mandeb shipping lanes enable the Houthis to deploy a broader array of weapons to attack or harass vessels, including missiles, drones, and even artillery, depending on whether the Houthis are able to continue to consolidate control along the Red Sea coastline. Closer positions to the Bab al Mandeb can also ease the Houthis’ ability to surveil vessels or even impose fees and other coercive measures similar to those Iran has attempted to establish in the Strait of Hormuz.

The Houthis exploited military developments in southwestern Yemen in recent days to conduct an offensive against ROYG-aligned forces along the Red Sea coastal plain and capture Mokha. The National Resistance Forces (NRF) and other ROYG-aligned forces launched a counteroffensive into the Houthi-controlled coastal plain of southern Hudaydah Governorate on September 5.[28] These ROYG-aligned forces conducted this counteroffensive in response to Houthi attacks on various ROYG-aligned forces, including the NRF, Southern Giants Brigades, and Homeland Shield Forces, in areas of Hudaydah and Taiz governorates between Yemen’s coastal plain and the western inland mountain ranges.[29] NRF and other ROYG-aligned forces may have intended to relieve pressure on ROYG forces near Taiz City, which the Houthis had partially isolated by September 5.[30] The counteroffensive temporarily opened a salient on the coastal plain that threatened Houthi ground lines of communication (GLOCs) between the Red Sea coast and the front line surrounding Taiz City.[31]

ROYG-aligned forces established control over Hays District in southern Hudaydah Governorate on September 5 and approached their intermediate objective of capturing al Jarrahi, a crossroad town located on a major Houthi GLOC between the Houthis’ main port at Hudaydah City and Taiz City.[32] ROYG leaders publicly discussed their intent to advance north across the coastal plain and capture Hudaydah City as a primary objective of this counteroffensive.[33] The ROYG messaging may have been an information operation to compel the Houthis to divert forces from the Taiz City front to protect coastal Houthi-controlled cities and territory, which are vital to the Houthis’ smuggling and supply networks and their ability to attack vessels in the Red Sea.[34] ROYG-aligned forces advanced north from defensive positions that they had maintained along the front line for years into open flatland that is difficult to defend.[35]

The Houthis launched an offensive on ROYG-aligned forces on the coastal plain overnight between September 9 and 10, likely in order to eliminate the ROYG counteroffensive’s threat to Houthi positions and ports on the coastal plain.[36] Local sources in Sanaa City, which is Yemen’s Houthi-controlled capital, told Saudi media on September 9 that the Houthis deployed a significant number of fighters from the capital to support fronts in southwestern Yemen.[37] Houthi reinforcements from central Yemen reportedly arrived at positions west of Taiz and on the coastal plain.[38] The Red Sea coastal plain’s flat terrain likely hindered ROYG efforts to mount an effective defense against reinforced Houthi assaults from the north and east. The Houthis’ assault from elevated terrain east of the coastal plain also reportedly compelled ROYG forces to withdraw from the salient in southern Hudaydah Governorate to avoid encirclement by Houthi forces, according to an Israeli geospatial analyst.[39]

The Houthis continued their advance south along the coastal plain on the morning of September 10 and captured the ROYG-held port at Mokha.[40] Mokha was, until its capture by the Houthis, the ROYG’s only major Red Sea port and the NRF’s operational and logistical headquarters.[41] [42] Houthi officials, fighters, and media broadcast messages during the September 9 and 10 offensive that urged ROYG-aligned forces on the coastal plain to surrender and receive full amnesty.[43] A US-based Yemen analyst posted geolocated footage of Houthi forces entering the Mokha city center on the morning of September 10.[44] ROYG officials and military sources later confirmed to international media on September 10 that the Houthis captured Mokha.[45]

It is unclear how far past Mokha the Houthis have advanced as of this writing. The Houthis reportedly advanced further south of Mokha before the Houthis announced that their forces ceased combat operations on the coastal plain in the late morning on September 10.[46] International media reported on September 10 that Houthi forces advanced south toward Dhubab after capturing Mokha.[47] Dhubab is the ROYG’s last remaining port city on the Red Sea following the Houthi offensive and is significantly smaller than the port at Mokha. A Houthi capture of Dhubab would effectively grant the group control over almost all of Yemen’s Red Sea coastline. ROYG military sources told international media on September 10 that ROYG-aligned forces were relocating from Mokha to Dhubab amid the Houthi offensive.[48]

The Houthis have reportedly attempted to seize ROYG-controlled islands in the Red Sea from which Houthi fighters could launch attacks on international shipping. Houthi forces reportedly landed on the Hanish Islands in the southern Red Sea on the morning of September 10 after conducting attacks over several weeks to isolate ROYG forces on the islands, according to international media and a US-based Yemen analyst.[49] ROYG political and military sources told international media on September 10 that ROYG forces have withdrawn from at least two of the three main islands in the Hanish Archipelago amid Houthi forces’ landings on the islands.[50] Regional media also reported on the afternoon of September 10 that Houthi forces captured Perim Island, which is in the middle of the Bab al Mandeb Strait off the Yemeni coast’s southwestern-most headland at Ras Menheli.[51] ISW-CTP cannot yet confirm that the Houthis have established control over the Hanish Islands and Perim, however. Control over the Hanish Islands and Perim Island would offer the Houthis favorable positions from which to launch fast attack craft and projectile attacks on international civilian vessels at close range, provided that the Houthis develop secure logistics lines to transport weapons and supplies from the Yemeni mainland.

The Houthis’ coastal plain offensive accomplished significant Houthi operational and strategic objectives that weaken the ROYG’s ability to disrupt Houthi operations and exert both short-term leverage over Saudi Arabia and possible long-term leverage over the international community. The Houthis have denied the ROYG access to its primary port on the Red Sea by capturing Mokha. This development is particularly damaging to the NRF–which was headquartered in Mokha before its withdrawal to Dhubab on September 10–because NRF and other ROYG-aligned forces had to abandon Saudi military equipment held in the city due to the swift pace of the Houthis’ assault.[52] ROYG forces are also less capable of disrupting Houthi smuggling routes and military operations in the Red Sea after withdrawing from Mokha. The Houthis depend heavily upon sea lines of communication in the Red Sea and Bab al Mandeb to import both civilian and military goods.[53] Port facilities on the Red Sea coast were vital to ROYG operations against Houthi smuggling and military activity. ROYG media claimed in late August 2026 that ROYG forces engaged and intercepted various Houthi small craft in the Red Sea, particularly in the vicinity of the Hanish Islands, for example.[54] The NRF also seized a shipment of drone components intended for the Houthis from a vessel reportedly traveling from Djibouti to Hudaydah City on August 24.[55]

The Houthi offensive campaign on the Red Sea coastal plain is part of a recent, broader shift in Houthi military activity that is intended to compel Saudi Arabia to submit to Houthi demands. The Houthis have targeted Saudi vessels less in recent weeks amid Saudi efforts to divert oil exports away from the Bab al Mandeb, according to Western media in August 2026.[56] The Houthis have instead increasingly targeted Saudi oil infrastructure and other sites in Saudi territory because the Houthis seek to compel Saudi leaders to submit to the Houthis’ terms by maximizing Saudi political and economic costs.[57] The Houthis’ demands include a Saudi withdrawal of all military forces and support assets from Yemeni territory, an end to the Saudi blockade on Houthi-controlled territory, payments of Houthi officials’ salaries, and war reparations for Saudi and ROYG-aligned military operations in Yemen.[58]

The Houthis’ capture of Mokha and possible control over islands in the southern Red Sea also provides the group with long-term leverage over international shipping. The Houthis could use a permanent force presence along the coastal plain and on islands in the Red Sea to attack international vessels in the future, as the Houthis are also enemies of the United States, Israel, and other international partners.

The Houthis have not yet indicated a firm intent to continue or halt their offensive, although the Houthis could attempt to capture remaining territory on the coastal plain south of Mokha in order to secure lines of communication with Perim Island and exert full control over Yemen’s Red Sea coast.[59] The Houthis’ reported halt to combat operations on September 10 does not indicate that the Houthis will cease their offensive entirely. The Houthis have several operational incentives to consolidate control over the entire coastal plain south of Mokha.[60] The Houthis would benefit relatively little from potential control over Perim Island if Houthi forces do not establish and maintain a secure overland route along which to transfer weapons and supplies to the island via Ras Menheli.[61] Control over the entire coastal plain would provide the Houthis with ease of access and secure logistics routes to Perim Island, which the Houthis could use to develop a military presence capable of striking vessels at close range in the Bab al Mandeb Strait.[62]

Saudi and ROYG forces reportedly conducted airstrikes on Houthi forces in the southwestern Yemen campaign area on September 10 amid ROYG forces’ likely efforts to regroup and prepare to recapture Mokha.[63] Houthi and Saudi media reported on September 10 that Saudi and ROYG-aligned forces struck Houthi forces moving along GLOCs between the Houthi-controlled mountains west of Taiz City and Mokha, as well as on roadways extending from Sanaa to southwestern Yemen.[64] ROYG military media warned civilians on September 10 to avoid roadways between Taiz City and Mokha and announced that ROYG-aligned forces will use “all types of weapons and air power” to establish a ”kill zone“ on the coastal plain in the vicinity of Mokha.[65] ROYG and Saudi forces do not appear to have attacked Mokha proper at the time of this writing, which suggests that ROYG forces likely intend to recapture the city. A retreating army is unlikely to destroy critical facilities that it intends and foresees a reasonable opportunity to recapture, particularly if that army depends upon the base significantly for military operations in the campaign area.