America is pivoting to Asia, focused on the Mideast, yet the "backyard," as Secretary of State John Kerry once referred to Latin America, is sprouting angry weeds as the scandal involving intelligence leaker Edward Snowden lays bare already thorny U.S. relations with Latin America.

South American leaders planned to send a tough message to Washington on Friday over allegations of U.S. spying in the region and to defend their right to offer asylum to fugitive former U.S spy agency contractor Edward Snowden. Capping two weeks of strained North-South relations over the Snowden saga, presidents from the Mercosur bloc of nations were meeting in Montevideo, Uruguay. Complaints against the United States were high on the agenda.

Sure, we've heard fiery speeches offering asylum from leftist leaders who are eager to criticize the United States. But supporting Snowden's cause and wanting to make Uncle Sam look bad aren't the only parts of the equation, with so many trade and diplomatic relations hanging in the balance, said Michael Shifter, president of the Inter-American Dialogue think tank in Washington.

Don't get me wrong. Venezuela is a great country, with friendly people and breathtaking natural beauty. There are Caribbean beaches and snow-capped mountains in the Andes. We should take a road trip: Gasoline costs just 1 cent a gallon. But you might have trouble buying a new car. At the very least, you'll need patience. Soldiers, police officers, and government officials have first dibs.

Suddenly, South America’s leftist presidents, whose hemispheric influence had been waning of late, found their mojo again. They rushed breathlessly to Bolivia to greet Morales, who shouted, “United we will defeat American imperialism!” while calling for the closure of the U.S. embassy there. By Friday evening, Venezuelan President Nicolás Maduro, in need of a political boost after just barely winning a special April election to succeed his mentor, the late Hugo Chávez, formally offered the “young American” Snowden asylum from “persecution from the empire.”

The Snowden affair provides a teachable moment for a great many things, not least of them the need for robust U.S. public diplomacy. Today more than ever, global public opinion matters. The U.S. cannot conduct itself with disregard for how its actions will be perceived by the rest of the world; even public diplomacy at its best cannot fix bad policy. But modern public diplomacy is not at its best.