World nations laid the foundation of the United Nations after catastrophic events of the World War Two. Was it a compulsion to move for collective peace after millions of killings and unaccounted destruction? Of course, yes. That was a compulsion and not a lesson because, even today nations are rogue again. They are at daggers drawn against each other on multiple matters. They are ready to bomb each other for exclusive interests and vested benefits. Consider the examples of countries like North Korea and the USA itself. None of the two will be taking a step back when their is clash for survival of the fittest.
Further, nation states are engaged in hypocrisy rather than diplomacy. They pledge at one thing but, back stab at another. Take the recent state behaviour of the USA. It pledged to stand firm with its allies but, today it is ready to defy its companions like European Union and NATO.
It won’t be wrong to state that, when it comes to interests, nations forget the past. They forget the aim for which they established institutions like UN. They forget the consequences of deadly wars. For temporary results, they make such decisions which lead the world towards long term crisis.