It has been a week since Yemen's Iran-backed Houthi rebels stormed down the Red Sea coast, extending their reach to the Bab el-Mandeb strait — a narrow passage through which about 12% of world trade passes in peacetime — and threatening Saudi oil exports.
The rebel blitz has forced some 125,000 people to flee their homes. An ongoing civil war in the country has killed over 150,000 people and at times pushed the country to the brink of famine.
Now the Houthis appear to be eyeing Yemen's oil-rich east.
So far, the only thing standing in their way is Yemen's Saudi-backed government and an array of forces that have fought each other as recently as January. Saudi Arabia's most important ally, the United States, appears to be sitting this one out.
The Houthis captured the important Red Sea port city of Mokha before taking several islands near the Bab el-Mandeb strait. The group is also just 32 kilometres from Djibouti, a small African nation hosting US and other military bases.
The Houthis first swept down from their northern heartland in 2014, capturing the capital, Sanaa, and much of northern Yemen. Saudi Arabia intervened the following year, and fighting raged until a 2022 ceasefire.
In recent days there has been heavy fighting in and around Marib, a central city in an oil-rich province of the same name. Previous Houthi offensives have failed to capture the city, which also serves as a military hub for Saudi-backed forces. The Houthis also threaten the western city of Taiz, a front line for much of the conflict.
The Houthis are firing at Saudi oil facilities and tankers. An attack on Saudi Arabia's east-west pipeline, blamed on Iran-backed militias in Iraq, added to an unfolding nightmare for the kingdom and rattled world markets.
The Houthis want Saudi Arabia to lift a long-running blockade on the territory they control.