Allende's form of socialism was distinct from the centrally planned soviet style economy, focusing on responding to problems and creating high level economic goals, but otherwise focusing on a self organizing, bottom up, worker led economy extremely distinct from the Soviet system.
This idea started actually working, and the United States fearing, in the CIA's own words, "a successful socialist experiment" tried everything they could to remove Allende and push the country away from socialism. They even looked at the idea of invading the country, but couldn't because of the public opinion of how poorly Vietnam was going. The most successful intervention was, in the United States government's own words again, "making the economy scream". However despite this Allende still kept being elected clearly in elections that no one has disputed the validity of.
So enough being enough, the US government backed one of the most brutal dictators ever, Pinochet, to illegitimately take over the government, killing Allende in cold blood and beginning a reign of terror. Theyd do stuff like rape your wife and children to death in front of you, so that when they took you out to sea on a "helicopter ride" to dump you at sea still alive, you welcomed death. We as the United States trained his staff in torture in the School of the Americas at Fort Benning, and provided an immense amount of funding. Over 10,000 people were killed.
To rebuild the economy after the intervention, they brought in the Chicago Boys, a set of Chicago school economists, to "unleash the economy" from the socialist practices of Allende, but it didn't really work. Chile's growth trailed the rest of South America's until those practices were rolled back.
And even now the scars of all this still exist in Chile, with the massive protests that have been going on for over a year focusing on demands to replace the terrible Pinochet era constitution, and state security forces openly killing protestors.