The influence of the US is bound to the strength of its economy, the strength of its economy is bound (currently) to its use of fossil fuels. So if the US acts preemptively, it loses its power to influence others to do the same, it drives up costs for itself while driving down fossil fuel costs for others, so their economy and thus influence increases. Yet, if (in the terms of A Beautiful Mind) "If everybody goes for the blond, nobody gets laid", which is to say if consumption can't be curbed, everybody is doomed.
But the problem, when you said: "tells EVERY NATION that they must partake" You have to ask "who does that?" The bottom line is the US doesn't have an enforcement capability in China, Russia or the rest. They are sovereign nations. In fact there is no world power which can make FORCE every country to do things, especially when their is so much benefit in them defecting.
So the politics actually look incredibly grim. The best hope here is something that can fundamentally alter the equation above, so that there is positive rewards for nations going green. That something would necessarily come from the best and brightest of science and business. An example would be an efficient fossil fuel combustion process that turns an engine while sequestering carbon into a valuable industrial product like carbon fiber... Something like that is more profitable to use than not use, making the transition natural.
I guess my point is, I think its a really good time for techies to start thinking way outside the box on this problem...