When trying to determine the real cause of actions by governments, I tend to doubt conspiracy theories and accept claims of inadvertence or incompetence. It's just too hard for large bureaucracies to get away with devious plans.
So when I read the disturbing report that a plane carrying a field hospital to Haiti, chartered by the well-respected Doctors without Borders, was refused landing rights, I wanted to know why. The French Government complained loudly, hinting that the United States did this in order to dominate the relief effort and take over the stricken country. [Of course, the French have more history with conspiracies than we do.]
Well, according to U.S. military briefers in Haiti [whose transcripts I regret I can no longer locate and link], that particular flight was diverted because an earlier plane was delayed in unloading its cargo. There was insufficient taxi and offload space, and air controllers did not want to shut down the main runway for the time required to offload the field hospital. Some other medical relief flights were denied permission to land because they had not radioed in advance and been given a timed landing slot.
Those explanations sound reasonable to me -- and seem much more credible than an anti-French conspiracy by some overworked airport operators.