Antonio Guterres, UN Secretary-General, called on Friday for a political solution to the 11 years civil war in Syria, that began and has devastated the country and its people.

The civil war began when the Bashar al-Assad regime cracked down on pro-democracy protesters. Hundreds of thousands of people have since been killed and millions more displaced, according to UN estimates.

“We cannot fail the Syrian people. The conflict must cease. International humanitarian law must be respected,” Guterres said in a statement. “I call on all parties to meaningfully engage in the UN-facilitated political process and appeal for further support to scale up the humanitarian response. We must choose peace.”

Guterres said the past 11 years of brutal conflict have exacted an unconscionable human cost, and “millions of internally displaced and refugees struggle to survive in the most difficult circumstances.”

But, he argued, “we must not lose hope,” move beyond “rhetorical commitments” to peace and to do all that is necessary to reach a negotiated political solution in line with Security Council resolution 2254 (2015). “This is the path to a solution that meets the aspirations of all Syrians,” he said.

The UN chief called for ensuring greater humanitarian access to address the needs of people throughout the country. “Cross-line and cross-border deliveries are essential to reach millions of people in need,” he said.

Guterres also urged “collective action” to end the practice of arbitrary detention and forcible disappearance of tens of thousands of people. “It is time to respond to the urgent calls of families across Syria who are seeking to clarify the fate and whereabouts of their missing loved ones,” he said. “As families seek truth for their loved ones, thousands continue to languish in prisons in unimaginable conditions.”

Meanwhile, the office of the special UN envoy on Syria said a new round of talks involving a constitutional committee seeking a solution to the ongoing war will resume in Geneva from March 21.