As the Yemen war enters its twentieth month, the fighting has escalated beyond the country’s confines, with Iranian-backed Houthi rebels firing what appeared to be Iranian antiship cruise missiles at foreign vessels operating around the Bab al-Mandab Strait. The U.S.-flagged, Emirati-operated supply ship Swift was struck on October 1, and U.S. Navy ships were unsuccessfully targeted in subsequent days. In response, U.S. forces struck Houthi-controlled portions of Yemen’s coast, destroying three surveillance radars of undisclosed type that were reportedly active during the missile attacks.

While U.S. military sources have yet to confirm the type of weapons fired at their ships, the prime suspect is the C-802 Noor, a cruise missile system that Iran has reportedly provided to its traditionally anti-American Houthi clients. Two other possibilities cannot be ruled out yet. The first is the C-801, an older cruise missile in the Yemeni navy’s arsenal, which could have fallen into rebel hands given that the Houthis are allied with former elements of the country’s armed forces and have taken over significant territory. The second is a converted version of the S-75 (SA-2) surface-to-air missile. Since 2015, a majority of Yemeni radar and air-defense systems have been attacked and rendered useless by the Saudi-led coalition’s airpower due to fears that they would be employed by the Houthis or their allies. In January, however, IHS Jane’s reported that forces opposing the Yemeni government had converted at least some S-75s to strike at surface targets at significant ranges. These same weapons could theoretically have been used in the recent antiship attacks.

Whatever the case, the threat that Houthi antiship missiles pose to international shipping is real. And while Iran may have sent C-802 missiles to the rebels well before the current war began in 2015, it could still further help the Houthis improve their tactics, equipment, and targeting effectiveness by supplying them with other systems and expertise. To be sure, such transfers would be a difficult task under the current circumstances — unlike with other regional militia clients such as Hezbollah, Iran does not presently have a known, direct line of supply to the Houthis, and the coalition has reportedly seized several dhows carrying sporadic shipments of Kornet antitank missiles and other weapons for the rebels. A supply route via the Suez Canal and northeastern Africa might be more practical, though still problematic. And unlike in Syria, Iran can no longer supply the Houthis by air either. In April 2015, Saudi fighter jets prevented an Iranian plane carrying passengers and cargo from landing at Sana airport, and no Iranian aircraft have been permitted to land in Houthi-controlled territory ever since.

Additionally, transporting potent antiship missile systems typically requires a decent-size cargo vessel, if only to better conceal the illicit arms. In March 2011, for example, Israeli forces in the Mediterranean Sea captured the 17,000-ton ship Victoria, whose cargo included six C-704 Nasr antiship missiles, two launchers, and two British-made maritime radars complete with hydraulic mountings. The Iranian missiles were intended to be offloaded in Alexandria, Egypt, transferred by land through the Sinai, and eventually delivered to Hamas in Gaza. The Nasr has a 130-kilogram warhead and is smaller than the C-802, but easier to transport and operate, and reportedly more effective. With a range of around thirty-five kilometers — long enough to reach almost any part of the Bab al-Mandab Strait — it can reportedly sink a 1,000-ton ship. Iran’s Zafar antiship missile has similar capabilities. The Nasr family also includes an electro-optically (EO) guided version, Nasr-e Basir.

Besides the Nasr and various C-802 derivatives (e.g., the Noor, Ghader, and Ghadir, with claimed ranges of 120, 200, and 300 kilometers, respectively), Iran also operates the lighter and shorter-range Kosar class of EO/radar-guided missiles with ranges of 15 to 25 kilometers. EO-guided weapons can be more difficult to counter, and if they enter the Yemen war, they could be fired at U.S. ships with little or no warning.

HEATING UP THE RHETORIC

Even as U.S. ships are being targeted in the Bab al-Mandab, Iran has been ratcheting up its rhetoric against the American role in Yemen. On October 10, senior Islamic Revolutionary Guard Corps figure Gen. Amir Ali Hajizadeh accused the United States of running the war, calling it a Hebrew-Arab-Western conspiracy to destroy the Yemeni people. This position was echoed by influential hardliner Ahmad Khatami three days later during Friday prayers in Tehran, traditionally a de facto outlet for expressing Iran’s foreign policy posture.

Meanwhile, on October 5, the Iranian navy sent its 44th antipiracy task force to the Gulf of Aden, where it will also monitor Western and coalition naval activities. The force includes the Vosper-class Alvand (71) frigate armed with Noor antiship missiles.

The U.S. Navy deployed its own task group to the Bab al-Mandab on October 3, right after the Swift attack. The missile attacks against the American ships did not start until after a deadly Saudi airstrike hit a memorial service in Sana five days later, killing and wounding hundreds of people, reportedly including high-ranking Houthi commanders. The timing of the initial missile attacks suggests they were revenge strikes against the highest-value targets at hand, which happened to be U.S. vessels (the Houthis also fired Scud missiles toward the Saudi city of Taif that same night).

Yet the fact that missile attacks reportedly continued days later could mean that the Houthis are also pursuing tactical objectives by attacking American warships. In an October 13 story in the Iranian outlet Fars News, rebel leader Abdul-Malik al-Houthi claimed that the U.S. counterstrikes on Yemeni mobile radar sites were Washington’s way of “preparing the ground for an aggression against the port city of Hodeida,” the second-largest Houthi stronghold in Yemen. He reportedly called for “resisting this savage aggression using all possible means.” The Houthi-controlled port has been a major destination for ships bringing supplies to the rebels, spurring the Saudi air force to bomb it in August. Any coalition attempt to cut Houthi territory in half would require a successful amphibious assault on Hodeida, so rebel leaders are keenly aware of its importance.

Alternatively, whoever was behind the missile attacks could have been trying to create a “Stark effect,” that is, a high-profile outrage similar to the missile strike that hit the USS Stark in 1987 and dragged the United States further into the first Gulf War. Although it is unclear what they could hope to gain by such an outcome, it should not be ruled out yet.

POTENTIAL FUTURE THREATS

Arguably even more dangerous than occasional missile strikes is the prospect of limited mining of coastal and international shipping routes, which the Houthis are capable of doing without direct Iranian help. The countermine support ship USS Ponce and other existing assets could help clear the Bab al-Mandab Strait under those circumstances, but such a move might still disrupt shipping in and around the area for weeks. It could also create disproportionate psychological effects on world markets.

In light of these current and potential threats, the United States needs to send a message to rebel factions in western Yemen that any escalation into the strait is unacceptable and will be met with a robust response, perhaps beyond the recent strikes on radar installation. At the same time, Washington and the international community should persuade the warring sides to enter a lasting ceasefire, since any greater U.S. involvement will further complicate a war that seems to have no end in sight.

Farzin Nadimi is a Washington-based analyst specializing in the security and defense affairs of Iran and the Persian Gulf region.

Originally Posted on October 17, 2016

©2016 The Washington Institute for Near East Policy. Reprinted with permission.