Yemen’s deposed former leader Ali Abdullah Saleh was killed on Monday during clashes in the capital city of Sana’a, marking a dangerous new turn in the country’s civil war. Three days earlier, Saleh had turned against his Houthi rebel allies, switching sides in a conflict that has been raging for roughly three years. Saleh’s gambit failed, however, as the Houthis were reportedly able to quell the brief uprising led by his forces. Images of Saleh’s lifeless body were broadcast around the world, with Houthi leader Abdel-Malek al-Houthi stating in an announcement later that day that Saleh had been killed for “treason.” He added, “The conspiracy of betrayal and treason failed, this black day for the forces of the aggression.”

The Yemeni war has already become one of the largest humanitarian catastrophes in the world, and the death of Saleh has the potential to make the conflict even worse. His brief turn against the Houthis and realignment with the Saudi-backed central government seemed to be part of a strategy by Saudi Prince Mohammed bin Salman and the leaders of the United Arab Emirates to turn the tide of the war and isolate the rebels. The Saudis had publicly welcomed Saleh’s about-face, but any hope of a radical change in the balance of power in the conflict appears to have been terminated along with Saleh’s life.

It is unclear what the future now holds for Yemen. Yet, by all accounts, the proxy war between Iran and Saudi Arabia taking place inside the country looks set to intensify. In recent weeks, Houthis have claimed responsibility for rocket attacks against targets in Saudi Arabia and the UAE, which Gulf leaders have publicly accused Iran of helping facilitate. Meanwhile, aerial bombardment and blockades of Yemeni territory, carried out with the assistance of Western powers, have put millions of civilians in the impoverished country at risk of mass starvation.

For better or worse — and largely for worse — Saleh helped make the modern state of Yemen what it is. For decades, he ruthlessly ruled over Yemenis, enriching himself and his own family in the process. He also succeeded in playing rivals off against one another and positioning himself as a counterterrorism ally of the United States, while also aligning with Iran and other parties when necessary. During the upheavals of the Arab Spring, Saleh acquiesced to a transfer in power, only to try and align with the Houthi rebellion in a bid to regain his old political preeminence. His death puts the exclamation point on the end of an era in Yemen that had, for all intents and purposes, already come to a close. It will be recorded in history books that the Saleh era in Yemen was torn down in a bloody civil war, amid a catastrophic humanitarian crisis the likes of which should never come to pass in the 21st century.