The US and Saudi Arabia have opposing strategic priorities in Yemen. The US has prioritized countering al-Qaida, while Saudi Arabia considers al-Qaida an equal threat to its security as Iranian proxies such as Hezbollah and the Houthis. 

Behind US humanitarian concerns for civilian casualties in Yemen lies another motivation: a growing inclination at least during the latter part of the Obama administration, undeclared but increasingly clear, to pivot away from Saudi Arabia in favor of its rival, Iran, which backs the Houthis. For this reason, the US has not reacted to Iran’s recent announcement that it plans to build naval bases in Syria and Yemen, which could considerably increase Iran’s support for the Houthis.

Iran, along with Hezbollah, provide money, training and ballistic missile technologies to the Houthis posing a threat to Saudi Arabia from the south, as the Houthis have overrun Saudi border guard headquarters and occupied 50 square miles of depopulated Saudi border towns. In April 2015,  US Secretary of State John Kerry asserted that Iran was providing military assistance to Houthi rebels. Brig. Gen. Ahmad Asiri, a military adviser to Deputy Crown Prince Mohammed bin Salman, told me that, to date, Saudi Arabia has intercepted 36 ballistic missiles fired indiscriminately by the Houthis. As the collapse of Yemen’s government enabled al-Qaida, Houthis and other local militias to organize, Saudi Arabia’s exit from Yemen would be met by the increased presence of al-Quds fighters of Iran's Revolutionary Guard, al-Qaida, Houthis and Hezbollah, all threatening regional security.

Broader Ramifications of the Conflict

Sunni-Shiite tensions in Yemen have global security and economic ramifications; tensions are affecting sailing routes of oil tankers leaving the Arabian Gulf. The Pentagon confirmed Houthi rebels in Yemen were responsible for launching cruise missiles at the US Navy destroyer Mason multiple times in October 2016. In the same month, the Houthis used advanced anti-ship missiles provided by Iran to target US, UK, and Emirati ships delivering medical aid to Aden and evacuating wounded civilians for treatment.

The increasing Iranian presence in Yemen and differing strategic priorities of the US and Saudi Arabia can adversely affect the United States’ capabilities to exert influence in the Gulf. Iran or Russia would be in a position to control the Bab el-Mandeb strait that connects the Red Sea with the Gulf of Aden and the Arabian Sea. This will most certainly occur if Iran builds a naval base along the strait, undermining the access and activities of US warships such as mine sweeping and coastal patrols. An Iranian naval base would prevent Saudi Arabia’s blockade of Yemen and likely lead to direct confrontation between Iran and Saudi Arabia. This could also prevent the trade route of two-thirds of global oil from the Arabian Gulf from reaching the Suez Canal or Sumed Pipeline. Iran demonstrated its naval aspirations in 2009 when it conducted exercises near the Gulf of Aden and in 2011 when Egypt’s Muslim Brotherhood granted Iranian ships access to the Suez Canal.

New Administration Reset

The Trump administration’s rejection of the Iran deal will likely be accompanied by a greater willingness to confront Iran’s building of naval bases beyond its borders and support for Hezbollah and the Houthis in Yemen. Preemptively targeting transit points for weapons prior to reaching Houthi fighters will likely reduce civilian casualties as Saudi Arabia will be less reliant upon faulty Yemeni intelligence. Neighboring Gulf states with Yemen are likely to be pressurized to provide intelligence on overland smuggling routes to interdict weapons along porous borders with Yemen.

Barak Seener is the CEO of Strategic Intelligentia and a former Middle East fellow at the Royal United Services Institute. He is on twitter at @BarakSeener.