Erik Ortiz, NBC News, July 25, 2014

Academic researcher Al Valdez was in El Salvador’s capital city two years ago watching bewildered deportees from America step onto the tarmac. The plane was full of undocumented immigrants sent back because of their criminal records, he said, including some gang members. A nun gave each one a banana or an aspirin, and told them they were free to leave.

There was no one offering to help rehabilitate them into Salvadoran society.

“I was disturbed. They were simply repatriated back into their country,” said Valdez, the author of books on Southern California gangs and a former supervisor with the Orange County District Attorney’s gang unit.

The lack of oversight has allowed gang members to assert control in El Salvador and neighboring countries, where tens of thousands–including unaccompanied children–have made dangerous journeys to the U.S. border in recent months. In addition, Valdez said, the United States’ own policy has been an unintended driver of the pile-up on America’s doorstep.

U.S. immigration policy was tightened in 1996, resulting in more undocumented immigrants convicted of crimes being deported to their home countries. That included expelling criminals familiar with gang culture in Los Angeles and other cities to their native El Salvador, Guatemala and Honduras–now among the most dangerous countries in the world.

“This American style of gangsterism was imported like a catalyst” and became mixed with the local gangs into a violent and murderous mash-up, Valdez said. “It took off like a wildfire, like a virus out of control.”

The most high-profile are rivals MS-13, formally known as “Mara Salvatrucha,” and the 18th Street gang, or M-18, both of which have roots in the U.S. It was in Los Angeles where Mexican immigrants formed the 18th Street gang, and then began recruiting Central American immigrants in the 1980s. MS-13 was made up of mostly Salvadoran immigrants who were trying to protect themselves from other gangs, Valdez said.

They effectively assimilated into the American gang lifestyle, getting tattoos, wearing certain clothes and learning how to recruit. But when the U.S. decided to clamp down on undocumented immigrants with rap sheets, they were sent back to Central America armed with what they learned in the U.S., said Magdaleno Rose-Avila, a Seattle immigration activist who has studied gangs in El Salvador.

{snip}

There have been reports of gang members in Central America threatening children, even killing them, when they refuse to join their ranks as foot soldiers. Kidnappings, stabbings and attacks on public transportation by gang members routinely grab local headlines.

{snip}

President Barack Obama met with the presidents of El Salvador, Guatemala and Honduras on Friday to discuss the border crisis and acknowledged that they have a shared responsibility to fix the problem. He suggested the possibility for a limited refugee program although that wouldn’t be enough to stem the tide of undocumented immigrants from Central America.

“We created the economic and political conditions there,” Rose-Avila said. “All these kids that came back and are disrupting the communities with gangs–we created that.”