Final answer:
The U.S. faced difficult challenges during the Vietnam War, including guerilla warfare tactics used by the Vietcong, an ineffective South Vietnamese army, and conflicting ideological ideas between communism and democracy during the Cold War.
Step-by-step explanation:
One difficult challenge the U.S. faced during the Vietnam War was the guerilla warfare tactics used by the Vietcong. The Vietcong would often engage U.S. troops in hit and run style attacks, making it difficult for the U.S. soldiers to identify the enemy and effectively fight back. Additionally, the Vietcong had networks of tunnels where they could hide and have bases for supplies and shelter, further complicating the U.S. military's efforts.
Another challenge was the lack of effectiveness of the South Vietnamese army. The soldiers were primarily conscripted and lacked faith in their own government, leading to a focus on self-preservation rather than confronting the communists. This hindered the U.S. troops' mission of supporting the South Vietnamese army.
Finally, conflicting ideas between communism and democracy during the Cold War played a role in U.S. involvement in Vietnam. The United States opposed communism and supported South Vietnam against the communists in the north. This ideological conflict resulted in the U.S. military becoming fully engaged in Vietnam.