The reappearance of injured Yemeni president Ali Abdullah Saleh should not distract from the disappearance of the Yemeni state. Yemen has been torn apart by months of unrest and at one point was on the verge of civil war. Instead of an all-out armed conflict, localized fighting has challenged state control. Taiz, a former capital and the country’s third-largest city, is contested. Aden, the former capital of South Yemen and the second-largest city, has largely been left to the southern secessionists. Meanwhile, al-Qaeda-linked militants, calling themselves “Ansar al Sharia,” have begun to carve off large swathes of territory in the south. These militants are also poised to seize Aden, which will open up control of the south to al-Qaeda.

Al-Qaeda’s presence in Abyan should be extremely concerning:

Zinjibar and Jaar have become destinations for militants. Should Ansar al Sharia defeat the Yemeni military in Zinjibar, Abyan would become a staging ground for an offensive to take the strategic city of Aden. The fall of Aden raises the possibility of the fall of the south, which will have resounding effects on the future of the Yemeni state. Al Qaeda would gain relative freedom of movement from the Arabian Sea to the Saudi border, significantly increasing the risk of an attack on an international or Saudi oil target, and could erect a form of an Islamist government in its territories. The Yemeni state would not only lose its southern port city of Aden, but would also lose revenues from southern oil. Should the Yemeni military or some other actor fail to halt al Qaeda’s advance, there is the very real prospect that al Qaeda could establish an Islamic emirate in south Yemen.

Saleh may still nominally control the Yemeni government, but that government is losing control over its territory. Why should we care? Possibly because Yemen’s loss has been al-Qaeda’s gain.

Should Ansar al Sharia sweep through the south, al-Qaeda in the Arabian Peninsula (AQAP) — already one of the most virulent al-Qaeda franchises — may acquire even more operating space. AQAP has masterminded two attacks on the United States in less than two years out of Yemen. Free reign in south Yemen exposes American lives to another attack.

— Katherine Zimmerman is an analyst and Gulf of Aden team lead for AEI’s Critical Threats Project.