António Guterres urged to take lead in securing peace in Ukraine or risk future of UN

The former staff members, including many former UN undersecretaries, urged him to raise his profile and be prepared to take personal risks to secure peace, saying the UN is facing an existential threat due to the invasion of Ukraine by one of the five permanent members of the security council.

"What we and the broader public want to see, though, is a political UN presence and public engagement, in addition to the UN's notable humanitarian response to the Ukraine crisis," the authors said.

"We want to see a clear strategy to re-establish peace, starting with a provisional ceasefire, and the use of the UN's capacity for good offices, mediation and conflict-resolution.

"That could include visits to the conflict-stricken areas, discussions with the opposing sides, even moving your own office temporarily to Europe, closer to the urgently needed negotiations and, thereby, indicating the UN's resolve to address this major crisis head-on."

There has been concern that mediation in Ukraine has been undertaken by actors ranging from Turkey, France, Israel, and Austria.

By contrast during the Cuban missile crisis in 1961, the newly appointed Burmese UN secretary general, U Thant, played a major role in de-escalating and then mediating the conflict between Russia and the US.

"We have decided to raise our voice out of concern for the existential challenge that the United Nations is facing in this historic juncture," they write.

"The Russian invasion of Ukraine severely undermines the post-world war two global order. It is the pinnacle of a series of threats to humanity's peace and security, shared prosperity and respect for human rights that the UN embodies."

Critics say Guterres has been immobilised due to the scale of the splits between the permanent members of the UN security council, as well as by votes in the general assembly that have revealed deep divisions including the expulsion of Russia from the UN human rights council.

Supporters of Guterres argue he has been as clear as he can in criticising the invasion as inexcusable and deplorable without jeopardising his professional role.

The authors of the letter admit they do not know if Guterres is involved in any behind-the-scenes mediation.

"We know that you care deeply about ensuring a positive impact of our United Nations on humanity and the planet, which will also mark your legacy at the helm of the world body," they write.

"We therefore implore you to intensify your personal efforts, deploying all capabilities at your disposal and acting upon lessons learnt from previous conflicts, for the cessation of hostilities and conflict resolution through peaceful means.