With respect to your first paragraph's discussion, is it a viable solution if nations/governments are taken out of the equation for response and recovery efforts? What I mean is should NGOs be in-charge of the response and recovery phases/mission areas in foreign lands?
In that manner, sovereignty of the impacted nation would not be threatened and perhaps the aid would be received more adequately without the political wrangling normally associated.
Regardless of the solution, I don't think for one second though that we can forget the United Nations' contributions and intervention in any foreign disaster/crisis relief.
They must be part of the solution whether we as Americans agree with their agenda or not.
What do you think about the US Government investing much more in NGOs for that foreign aid in times of international disasters/crises? Why?
Would the solve your "chain of command" dilemma?