If you're not willing to lead

From the BBC earlier today:

A chorus of boos rang out. And a member of Papua New Guinea's delegation told the US: "If you're not willing to lead, please get out of the way."

From the BBC a bit later today:

"The US has been humbled by the overwhelming message by developing countries that they are ready to be engaged with the problem, and it's been humiliated by the world community," said Bill Hare of Greenpeace.
"I've never seen such a flip-flop in an environmental treaty context ever."

Now I'm no pacifist, though I am generally against any war maneuver not used as a last resort -- once diplomacy has been exhausted, and once severe economic warfare (embargos, boycotts) has been applied, I think force is certainly justifiable to prevent an entity from committing, say, genocide (in Germany back when, in certain areas of Africa).

Would actions leading to immeasurable deaths, maimings, drownings, starvation, destruction of home/history/way of life, etc in future generations count as an equivalent of genocide? Shouldn't it? At what point will diplomacy be considered to be exhausted on my own country? Or has diplomacy already been exhausted?

I'm pretty fucking exhausted, myself.