1. In 1970, President Nixon ordered a ground attack on Vietcong bases in Cambodia.
Pres. Nixon believed attacking in Cambodia was necessary to forestall communist forces from attacking South Vietnam from that direction. But his decision was unpopular with some senior staff members, who resigned in protest, as well as with the American public, which did not want further escalation of the war. This was seen as essentially an invasion of Cambodia by the US.
2. At My Lai, American soldiers killed hundreds of Vietnamese civilians.
More than 500 civilians were killed by US soldiers in what was essentially a massacre. Women and girls were raped also. It was an instance of soldiers losing control and acting with sheer brutality. The government initially sought to cover up the incident, but the truth came out. It caused further anti-war sentiment at home in the United States.
