Why did the U. S have a hard time winning in Vietnam

The Vietcong, tactical warfare, and they unfamiliar to the land. The morale of the troops were also extremely low due no good reason for the US to participate in the war.

Answer: First we must state the US was not at war but to answer your question the US had a hard time winning their because of multiple things. The Vietcong hid very well and ambushed US troops and the foliage around the area was thick with leaves and plantation where the Vietcong hid to ambush Americans. And another thing the US would have never been brought into this mess if France left once the US troops got there.