The International Maritime Security Construct issued a warning for vessels traveling thru the vital Bab al Mandeb Strait and the Red Sea just two days after the Houthis threatened to attack international shipping.

“The approaches to the Bab al Mandeb continue to be an area of concern,” the International Maritime Security Coalition (IMSC) – Coalition Task Force Sentinel said in an advisory issued on Nov. 16.

“When choosing routes, orient toward creating maximum feasible distance from Yemeni waters,” the IMSC continued [the emphasis is in the original IMSC advisory]. “Recommend transiting at night when possible. This will reduce the likelihood of visual identification by malign actors.”

The IMSC did not identify any of the “malign actors,” but it is clear the warning was issued in response to threats from Ansar Allah, the Iranian-backed militia that is also known as the Houthis and controls a large portion of Yemen, including the capital of Sana’a.

“We will sink your ships,” the Houthis declared in Arabic, English, and Hebrew on a graphic released on Nov. 14 showing an Israeli commercial vessel in flames.

The Bab al Mandeb Strait is a strategic maritime chokepoint that connects the Red Sea to the Gulf of Aden, permitting vessels to transit from the Indian Ocean to the Mediterranean Sea. Millions of barrels of oil flow through the strait daily. According to some estimates, roughly 9 percent of total seaborne-traded petroleum passes through the Bab al Mandeb.

IMSC, which was established in 2019, seeks to “provide reassurance to merchant shipping in the Middle East region through the contribution of a multinational force of ships, personnel and advanced capabilities.” Current members include Albania, Bahrain, Estonia, Jordan, Latvia, Lithuania, Romania, Saudi Arabia, Seychelles, the United Arab Emirates, the United Kingdom, and the United States. Focusing on the Strait of Hormuz and the Bab al Mandeb, Coalition Task Force Sentinel attempts to maintain “freedom of navigation, international law and the free flow of commerce to support regional stability and security of the maritime commons.”

The Houthis have raised the stakes in the Red Sea since Hamas’ brutal Oct. 7 terror attack on Israel. The Houthis have fired cruise and ballistic missiles toward Israel several times. U.S. warships, as well as Israeli air defenses and aircraft, have intercepted Houthi missiles over the Red Sea. Around Oct. 19, the U.S. Navy’s guided-missile destroyer Carney, intercepted four cruise missiles and 19 drones. In addition to the actions of Carney, Saudi Arabia intercepted a fifth cruise missile, according to The Wall Street Journal.

The Houthis shot down a U.S. military MQ-9 Reaper unmanned aerial vehicle earlier this month as it was operating near Yemen in international airspace. The U.S. military has yet to respond to the Houthi provocations. Although, in an apparent act of self-defense on Nov. 15, the USS Thomas Hudner, a naval destroyer sailing near the Bab al Mandeb, shot down a drone heading toward the ship.

The Houthis have threatened international shipping and U.S. naval vessels several times over the past decade, launching dozens of attacks in the Red Sea since 2015. The Houthis fired anti-ship cruise missiles at a U.S. Navy destroyer, the USS Mason, in 2016 while it was operating in international waters near Yemen. In 2018, the Houthis, under the direction of Iran’s Islamic Revolutionary Guards Corps, attacked two Saudi oil tankers. In 2020, Saudi Arabia intercepted several Houthi suicide speed boats, while the Houthis deployed hundreds of mines in the southern part of the Red Sea.

These threats to shipping by Tehran’s proxy are part of a larger strategy of the Islamic Republic of Iran. In fact, from January 2021 to July 2023, Iran perpetrated at least 26 harassments, attacks, or seizures of commercial and U.S. naval vessels.

The IRGC increasingly co-opted the Houthi movement since its formation in the 1990s. The IRGC has provided the Houthis with weapons, training, and financial support. The Trump administration listed the Houthis as a Foreign Terror Organization in Jan. 2021, but President Biden revoked the designation just weeks after he entered office. However, Abdul Malik al-Houthi, the group’s overall leader, Abd al-Khaliq Badr al-Din al-Houthi, and Abdullah Yahya al-Hakim remain listed as Specially Designated Global Terrorists.

The Houthis are estimated to have 100,000 fighters under arms. The official motto of the Houthis is: “God is great, death to the U.S., death to Israel, curse the Jews, and victory for Islam.”

Iran is leveraging its network of militias and terrorist groups in Yemen, Iraq, Syria, and Lebanon to put pressure on Israel as well as the United States. Iran’s proxy groups, including the Houthis, as well as the Iraqi and Syrian militias which number in the hundreds of thousands, enable Tehran to attack its adversaries while displacing the consequences to others. Many of these militias are battle-hardened by years of fighting the U.S. in Iraq as well as against Al Qaeda and the Islamic State in Iraq and Syria.

Bradley Bowman is the senior director at the Foundation for Defense of Democracies’ Center on Military and Political Power (CMPP). Bill Roggio is a Senior Fellow at the Foundation for Defense of Democracies and the Editor of FDD’s Long War Journal.