UNITED NATIONS (AP) — Only dialogue and diplomacy can end the devastating war in Ukraine, with total victory on the battlefield impossible for either warring party, members of a group of prominent former world leaders founded by Nelson Mandela said Friday.

The group, known as The Elders, delivered that message to Ukrainian President Volodymyr Zelenskyy, telling him on a visit to Kyiv this summer that he must start considering a way out of the conflict, former Irish president Mary Robinson who chairs the group known as The Elders said in a meeting with Associated Press executives.

“We need to encourage more thinking about how it will end in order to get the idea that this needs to end, as opposed to increasing the military arsenal on both sides and the devastation to the population in Ukraine,” said Robinson, who also served as United Nations (UN) high commissioner for human rights.

The Elders have condemned Russia’s February 24 invasion of Ukraine as “a flagrant violation of the United Nations Charter and a reckless, unjustifiable act of aggression that threatens to destabilise world peace and security.” In late September, The Elders also condemned Russia’s illegal annexation of four Ukrainian regions and defended Ukraine’s right to defend its territory and sovereignty.

Zeid Ra’ad al-Hussein, a previous UN human rights commissioner, agreed that diplomacy and negotiation were the only way out of the war, but he stressed that did not mean asking Ukraine to cede its sovereignty, since it was the victim of unprovoked Russian aggression.

He hinted that a settlement of the conflict could instead involve Russia receiving a concession “from another direction,” a possible reference to (North Atlantic Treaty Organisation) NATO, or one of its key members. Russian President Vladimir Putin has long complained the Western alliance has been pushing closer to its borders, a reality he has cited in justifying the invasion.

Former Mexican president Ernesto Zedillo said that despite economic sanctions imposed by the European Union and the United States “the flow of resources to finance this war has continued,” including the huge influx of oil revenue to Russia.

“I think there should be less hypocrisy about the way in which this bellicose economic war is being fought,” he said.

Zedillo also accused Russia of committing crimes that the International Criminal Court is charged with addressing — genocide, war crimes and crimes against humanity — and that have to be decided by “due process.”