This. The president sometimes is unable to fulfill promises because he is incapable or does not have the resources to make them come true.
The U.S., in my opinion, interferes with pretty much everything. Obama tried "persuading" (or so I've heard) China to raise the value of the RMB (or Yuan or whatever you call it) because too many people in the U.S. were going to China to manufacture their products and export it back to the U.S.
Clarification please. Are we specifically talking about U.S. politics or global politics?