It’s a party. Break out the tear gas.

It’s been 19 years since North and South Yemen were united into one country, which remains among the poorest in the Arab world. Yet regional divisions remain. Last week, as the government marked the date—parading 30,000 men through the capital of Sanaa, in the north, in a show of military might—violent demonstrations erupted in the southern port city of Aden. Escalating tensions have some observers worrying a civil war could be on the horizon.

At the commemoration ceremony, seated behind a wall of bulletproof glass, President Ali Abdallah Saleh oversaw the procession featuring elite troops, Russian-made tanks and fighter planes. But in Aden, roughly 3,000 gathered at an unauthorized rally to protest worsening living conditions, and alleging discrimination from the government in Sanaa. Police fired live bullets and tear gas into the crowd, killing at least three protesters and wounding 30 more, according to media reports. Another 120 people were arrested.

Regional tensions are long-standing: although most of the country’s oil facilities are located in the south, the population there (around four million) is worse off, and dwarfed by the north’s 20 million people. An attempt at southern secession in 1994 was stamped out. Yet the independence movement is gaining momentum: in April, for example, Tariq al-Fadhli, an ally of Saleh, abandoned the president and joined the secessionists. Tensions have only been aggravated by the economic crisis, which has hit Yemen hard. Following the violence, Saleh appeared on national television, calling on “all political groups and non-governmental organizations on the national Yemeni scene [to join] the national dialogue, as it is the ideal means to solve issues that are important to the nation.” Despite these words—and unification’s anniversary—the chasm that divides north Yemen from south, it seems, still runs deep.