Hans Grundberg argued that it was "still possible" to resolve the crisis in impoverished Yemen, where Iran-backed Houthi rebels control much of the nation.
However, the growing regional escalation brought on by Israel's genocidal onslaught on Gaza has essentially put a stop to any possibility of putting a plan into action.
Although preparatory discussions are continuing with all sides, "obviously... it cannot stay like this forever", Grundberg said in an interview at the Manama Dialogue conference in Bahrain.
"At a certain point, there is an expected delivery that the parties want to see happen. And if that doesn't take place, you risk losing the necessary momentum that you have.”
He added: "There are belligerent voices in the region. What I'm saying is, don't go down that road -- it's possible to settle this conflict."