Why does the Left attack the U.S.?

Ninety-seven percent of the slaves sold by black African tribal leaders and Muslim slave traders to the Portuguese, Spanish and English slave traders went to South America and the Caribbean Islands. About 350,000 were sold in the English colonies and that was outlawed by the Constitution. But even before the Constitution, the Northwest Ordinance (ratified 1787) had already outlawed slavery, as had many states.

So why isn't the Left attacking Brazil or Colombia for what happened three centuries ago? 10,000 slaves arrived in Cartagena every month in the 17th century. After the 17th century the largest slave trade moved to Buenos Aires (Argentina). There are more slaves today in the "enlightened" 21st century than in the 17th and 18th centuries, and most of the slave trade comes from Africa without the assistance of western European counties.

Only the United States is a threat to Leftists, now controlling the Democrat party. So it must be attacked.