i didn't expect this to explode but since it did, i'll elaborate a little on this

in 1970 allende was the first democratically elected, openly socialist president in history. he enacted many social policies despite being antagonized by most of the senate, and people will attest to the relative success of said policies

however, the US was still in the cold war, and they weren't going to let a socialist government flourish in their "backyard" that is to say, south america