Final answer:
The My Lai Massacre and its cover-up by the U.S. military deepened divisions within the U.S. and contributed to the public's growing opposition and mistrust toward the Vietnam War and the government.
Step-by-step explanation:
The question pertains to the My Lai Massacre, which occurred during the Vietnam War and involved U.S. troops indiscriminately killing civilians in a Vietnamese village. This massacre sparked international outrage and created deep divisions within the United States. It became a symbol of the war's brutality and raised questions about the moral and ethical conduct of the military. The incident was initially covered up by the U.S. military, but exposure led to a public trial and the conviction of Lieutenant William Calley. The Mai Lai Massacre and its subsequent cover-up by military personnel not only heightened tensions within the United States over the Vietnam War but also contributed to an increasing distrust between the American public and its government.