During the Vietnam War, the media was influenced by the public while the public was also influenced by the media. This happened for various reasons, but an important one is that the war was one of the first ones to be properly televised and people were receiving constant updates of the situation in Asia.
People were generally against the war, and it very soon became an extremely unpopular idea. The media realized this, and much of its broadcasting focused on tragic stories and horrifying images.
Naturally, this created a cycle, because the images and reports produced by the media increased the dislike that people had for the war. Therefore, the media in turn influenced the people, decreasing support for the war.