The successes of the Iran-backed militia "may create the conditions for the Houthis to try to establish themselves as legitimate leaders and guarantors of passage through the Strait, as Iran has tried to do in Hormuz," writes the think tank ISW.
On Friday, however, the Houthi movement tried to calm the outside world.
Free shipping and international trade in the Red Sea and Bab al-Mandab are taking place in an orderly and secure manner, spokesman Hazim al-Assad told the media outlet Al-Araby Al-Jadid, assuring that there is "no reason for international concern."
According to another spokesperson for the movement, all shipping is safe “for everyone except Saudi-owned ships.”
“The Strait of Sorrow”
The question is how much the world markets trust it. All global maritime traffic via the Suez Canal must pass through Bab al-Mandab – which roughly means Strait of Sorrow – between the Red Sea and the Indian Ocean.
The importance of the trade route has grown further since the Strait of Hormuz – on the other side of the Arabian Peninsula – has often been closed this year due to the US war against Iran.
With Iranian help, the Houthis have controlled large parts of Yemen for more than a decade, in conflict with a rival government backed by Saudi Arabia, which shares a 1,300-kilometre border with Yemen. Now the movement is carrying out a lightning offensive south along the Red Sea coast, and this week captured the port city of Mocha.
In the middle of the strait
According to media reports, they also control the Hanish Islands, just north of the narrow Bab al-Mandab Strait, and the island of Mayyun (Perim), which is located in the middle of the strait and divides it into two shipping lanes.
"Everything that was under control on the west coast has fallen," says the AFP news agency's source within the internationally recognized government.
Saudi Arabia has responded by attacking Mocha airport, reports a TV channel in the Houthi-controlled areas.
Trump is nodding
According to sources who spoke to the news site Axios, Crown Prince Mohammed bin Salman, who effectively rules Saudi Arabia, also called US President Donald Trump twice on Thursday to ask him to order attacks against the Houthis. But Trump said no, according to the sources.
Earlier this summer, bin Salman reportedly assured Trump that the Saudis could handle the Houthi forces themselves. But since then, the militia has had great success on the battlefield – and according to ISW, has also been able to take over weapons that the Saudis donated to their allies in Yemen.
The so-called Houthi movement – officially Ansar Allah (approximately Followers of God) – has ruled a large part of war-torn Yemen for a decade.
The Shia Islamist movement originated in the Zaidi al-Huthi clan, which has historically held sway in northwestern Yemen. It grew and radicalised in opposition to Yemen's involvement in the US war on terror in the 2000s.
In the wake of the Arab Spring, the movement went to war with Yemen's internationally recognized government, in a situation shaken by popular protests and southern Yemeni separatists. The Houthis were supported by Iran, while the government is supported by a Sunni coalition led by Saudi Arabia. Hundreds of thousands of people have died in the conflict that is still ongoing. Houthi forces seized power in the capital Sanaa in 2015.
The Houthi movement, part of Iran's regional coalition with the Palestinian Hamas and Lebanese Hezbollah, has shelled Israel and cargo ships in the busy shipping lanes off Yemen in recent years of war in the Middle East.
