The campaign along the Red Sea coast of Yemen is a miniature version of the problems facing the Saudi-led coalition seeking to reinstate the legitimate president of Yemen to power. The expected battle to wrest Hodeidah, Yemen’s largest Red Sea port, from control of the insurgent Houthis, brings these problems into sharp focus.

The Saudis and Emiratis enjoy an overwhelming preponderance of power at sea. The Emiratis have used this power to conduct two opposed amphibious landings, one in Aden and one in Mukalla. Both landings are unprecedented events for an Arab state. In the Red Sea, coalition forces’ naval vessels rely on freedom of maneuver, and look to dominant naval powers such as the United States and France to maintain this freedom of navigation, which is essential for their counterinsurgency strategy as well as  for commercial shipping transiting that waterway. As is the case elsewhere in the Yemen war, however, operational success has not translated into strategic victory. At sea as on land, the Saudi-led coalition appears to be no closer to achieving its goals than it was at the beginning of the war.

The conflict has settled into stasis. Coalition ground forces led by the Emiratis are in control of Marib but are unable to advance west to Sanaa across heavily defended mountainous, and reportedly mined, terrain. Also led by the Emiratis, coalition forces in Aden have pressed inland as far north as Taiz, but are unable to take what remains of the city from the Houthis and forces loyal to former Yemeni President Ali Abdullah Saleh.

Stalemate Inland, Opportunity along the Coast

With a stalemate setting in on the ground, and harassed by missiles fired by the Houthis well into the interior of Saudi Arabia, the coalition turned its attention early in 2017 to the areas along the Red Sea coast still held by the Houthis. Beyond the small ports of Mokha and Dhubab lies the prize: the major cargo port of Hodeidah, the only modern container port held by the Houthis and a probable shipment point for Iranian weapons.

Operation Golden Spear, launched on January 6 by the coalition, sought to seize Taiz and the Red Sea coastline south of Hodeidah. The offensive became bogged down in Taiz, but managed to seize Mokha and Dhubab. The coalition was set to move up the coast to Hodeidah as soon as it could consolidate its gains.

At the start of March, the assault on Hodeidah appeared imminent. Tactically, Hodeidah makes an attractive target for an amphibious landing. Unlike the eastern port of Mukalla, the working area of the port is located some distance away from the inhabited areas of the city. The city itself is surrounded by desert: The port could be seized and controlled without messy and difficult urban fighting. Saudi naval bases in Jizan and Emirati bases in Eritrea and Somalia would be able to stage and support land forces advancing up the coast from Mokha in the south. The fall of Hodeidah seemed to be a matter of when, not if.

The Prize Recedes

In the past two weeks, two major factors have changed this calculation. The first event was the March 11 death of two Yemeni coast guardsmen while trying to neutralize a naval mine near Mokha, which was presumably laid by the Houthis, or an allied group. So far there have only been two instances in which naval mines have caused damage, but mines are effective simply by creating uncertainty and indecision. The actual number of mines is unknown – but even the risk of a mine strike changes shipping practices. By deploying an indiscriminate weapon in critical commercial shipping lanes, the Houthis have signaled to the world that they are prepared to expand the scope of the war beyond Yemen and Saudi Arabia into areas such as the Red Sea, where noncombatant countries’ interests may be affected.

Laying mines has a profound tactical implication as well. The coalition naval forces will have to operate with a greater degree of caution than in the past. The presence of mines, especially when considered alongside what the commander of the U.S. 5th Fleet suggested was a remote-controlled boat attack in February against the Saudi vessel Madinah, hinders military control at sea and injects another element of complexity into a possible amphibious landing.

The second development, which was much more damaging for long-term coalition interests, was the deadly helicopter attack on March 16 against a boat loaded with Somali refugees fleeing the port of Hodeidah for Sudan. Media reports and human rights organizations blamed the coalition for killing the Somalis, although responsibility has yet to be fixed. In the wake of the attack, Saudi Arabia called on the United Nations to assume control of the port of Hodeidah.

The Way Ahead

The Saudi reaction is a canny one, insofar as it recognizes the importance of international public opinion in the war for Yemen, but it also reflects the long-term strategic weakness of the coalition. Saudi actions in Yemen have increasingly risked isolating the kingdom from its main strategic allies and weapons suppliers: the United States and Britain. While President Donald J. Trump seems inclined to ramp up the sale of advanced weapons to the Saudis, Congress maintains an important role in weapons sales, and may not share Trump’s views. Fatal mistakes are inevitable in warfare, but public opinion in the West is generally not favorably inclined toward the rentier states of the Gulf, especially Saudi Arabia.

The United Nations has refused to take over Hodeidah. But the Saudis probably never expected it to do so. Rather, by calling for neutral administration of Hodeidah, Saudi Arabia is attempting to inoculate itself against subsequent criticism of civilian casualties that may occur during the battle for the port.

Also restraining the coalition is the impending release of precision guided munitions from the United States. The Obama administration had held onto weapons that were due to be shipped to Saudi Arabia; the Trump administration appears prepared to resume the shipments, although not immediately after the attack on the Somalis (even if the Saudis deny responsibility for the attack). Similarly, the Trump administration would find it difficult to resume shipments while a major city was under siege. Nevertheless, a military assault on Hodeidah could follow within weeks of a U.S. weapons shipment to Saudi Arabia.

In the meantime, Saudi Arabia and the rest of the coalition may seek to step up naval blockades, preventing cargo from entering the port. Once the coalition feels it has a strong enough position along the coast south of Hodeidah, it will be driven by strategic logic to move against the last Houthi-controlled sea port.

The Wider Implications

The Saudi-led coalition fighting in Yemen has shown an unprecedented level of operational expertise for a modern Arab army, particularly a coalition force. Obstacles impeding the execution of its plan to take Hodeidah have, however, highlighted the limitations of tactical success in an uncertain strategic environment. The coalition cannot afford to leave Hodeidah unconquered; it just can’t afford the risk of undertaking its assault on the port city right now.

DB Des Roches is the senior military fellow at the Near East South Asia Center for Strategic Studies at the National Defense University. These remarks do not represent the views of any branch of the U.S. government.