What difficulties did United States soldiers face in Vietnam?

I have heard that they got what was called Jungle Rot or a foot fungus which made them raw and also made them burn from what I understand. I also have read that the weather in Vietnam is unpredictable and it could be hot and humid or it could be very rainy. They were also not familiar with the geography which was another problem. The jungle, humidity and the need to avoid fighting in populated areas were all problems. The lack of leadership in devising a strategic overall plan for fighting an insurgent war was a major problem.