Yemen’s ousted leader, Abd Rabbuh Mansur al-Hadi, reappeared in the port city of Aden on Saturday and said he was still the country’s president, raising the chance of a territorial breakup with the Shiites who control the capital, Sana’a.

Hadi had been put under house arrest when Houthi rebels from the north of Yemen stormed Sana’a in September.

Earlier this month, the Houthis formalized their takeover by dissolving parliament and forming an interim assembly to elect a presidential council.

Leaders from various political groups, including the former defense and interior ministers, attended a ceremony in the presidential palace in Sana’a during which the measures were announced, suggesting that the Houthi usurpation had been endorsed by other factions.

However, Hadi said the Houthis had staged a “coup” and described their political maneuvers as illegitimate. He reiterated his commitment to constitutional reforms that would split Yemen up into six autonomous regions.

The Houthis, a Zaidi Shia rebel group that advocates autonomy for the north of Yemen, rejected the partition plan, arguing it would undermine Yemen’s unity by strengthening Sunni and pro-Saudi fiefdoms.

Separatists in the south criticized the plan as well, fearing it would dilute their power over oil reserves in the Hadhramaut area.

Hadi’s flee to Aden raises the possibility that Yemen falls apart along pre-unification lines.

Adan was the capital of communist South Yemen, a former British protectorate, between 1967 and 1990. That year, it was unified with the northern Yemen Arab Republic. The south declared its secession four years later, prompting a civil war and northern occupation in 1994.

Al Qaeda has taken advantage of the country’s poor governance to establish what is considered to be its most dangerous international branch in the south of Yemen while the Houthis had been fighting the central government since 2004.

The Houthis are seen by American allies in the region, including Yemen’s neighbor, Saudi Arabia, as proxies for their nemesis, Iran. To what extent the group coordinates with Iran is unclear but their takeover of Sana’a has heightened Saudi fears of Iranian encirclement.