Officially, the United States claimed that it bombed Cambodia to stop the flow of supplies along the Ho Chi Minh Trail and to disrupt North Vietnamese military sanctuaries. However, many historians believe that the United States also bombed Cambodia to weaken the Cambodian government and to prevent the Khmer Rouge from taking power.
As the bombing continued, the United States also became increasingly concerned about the humanitarian impact of the bombings. The bombings caused widespread civilian casualties and created a refugee crisis. In addition, the bombings destroyed much of Cambodia's infrastructure, including its hospitals, schools, and roads. As the war progressed, the United States realized that the bombings were having little impact on the war, and they eventually stopped the bombing campaign in 1973.
Some historians also argue that the United States bombed Cambodia as part of a plan to overthrow the Cambodian government and install a pro-American regime in its place. This was never explicitly stated by the US government, but there is some evidence to support this claim.
In the end, the United States' bombing campaign in Cambodia was a failure. It did not achieve its goals, and it caused widespread destruction and civilian casualties. The bombing campaign also contributed to the rise of the Khmer Rouge, who would later perpetrate one of the worst genocides in human history.